Unless you are going to specifically blame one party or the other, I think you would be able to say what you want. I will say that there are lots of reasons for wages for falling and for this discussion one of them was women entering the work force which increased the labor pool and depress wages and also depressed birthrate. We can argue academically on objective facts that happened in the past. My point is people in the past and currently are poorer and in some cases much poorer than modern societies but have higher birthrates. For a society that can control its birthrate through medical and social means maintaining a stable level of population looks like it is going to need a conscious choice by that society.
Then the top of the food chain needs to prioritize paying us plebs instead of saving up for their next super yacht.
Fact is, an average educated mid-20 something with some support and didn't make stupid decisions with their choice of college is looking at ~$30K in debt and a ~$50K job. This is not a cost prior generations were saddled with. The actual number is higher than that, but it's heavily skewed by the coasts where the CoL is significantly higher. So for the sake of this example, let's paint an example elsewhere to demonstrate sacrifice-
I chose to live in misc suburb of misc flyover city and still can't afford a family!
But anyway, that mid-20 something isn't going to be able to pay much more than the minimum on their student loan debt, it'll hover over them until they're in their 40's, starting at a rate of about $5K per yr. They also have other expenditures to budget their elders didn't (yes this is a trend). i.e. no, they don't need the latest iphone, but they need a phone (and internet), and off the top of my head I'd very surprised if that can be done for under $2K per yr. These costs aren't needle movers for those of us mid-career, but they add up very quickly for those just starting - probably 15-20% of their pre-tax wages. This only makes it that much more burdensome to save up for the big one- a down payment on a house.
It'd be one thing if it the environment were like pre-covid but the all cash, above asking, inspection waived market that developed then is still alive and well - only now it comes with a 6-7% interest rate. This is not a cost prior generations were saddled with. Yes, I know interest rates were much worse in previous decades, but the annual income : down payment ratio wasn't anything like it is now. So they have to come up with minimum ~$25K for a down payment then be able to afford ~$1700 per month just to get in a house. Assume to this point these now spouses were fiscally responsible starting off- they sought out roommates, spent frugally, and minimized travel. It's still going to be a bear to get by paying less than $10K per yr in rent...each. That's more than 20% of their pre-tax wages and we haven't gotten to transportation (used car + insurance --> $6K per yr?), health care (healthy + ACA --> $5K per yr?), food (if very frugal --> $4K per yr?), and other essentials (utilities / clothes / toiletries / etc - $5K per yr?). Before we even consider the subject of saving, multiple the 2 together and we're at ~$75K in spend with ~$100K of pre-tax income. Tax obviously varies, but I like round numbers, so let's call post tax income $80K. Now, they're could be some corner cutting, especially with transportation (either bike or bus), but doing so limits rental options and increases the tax rate (urban living costs more than rural).
Put all this together and each of them have about $5K per year to put towards savings - whether that's investments, rainy day fund, or down payment for a house. And doesn't consider contingency - stuff breaks, including humans. Now, mid-20 somethings won't be able to invest according to general guidance, but it'd be real stupid not to invest anything, right? $2500 is not enough, but pragmatically, can this couple go any further? Similar story with the rainy day fund- they won't be able to store away 6 months worth of living expenses, but $100-150 per month adds up over time so budget $1250 per yr. That has an expiration date, if it's not needed, but then those dollars need shifted to investments because we're already years behind, so call it a wash. That leaves $1250 per year to save for a house. Put both budgets together and you have $2500. Basic math says they're 10 year out from considering buying a home.
Now, let's assume that happens- economies of scale kick in once you're living together. Some of those costs cool, but they quickly evaporate with maintenance on the house and furnishing it. For simplicity's sake let's call it a wash as well, but now we're building equity! But anyway, we're mid 30's and finally in a house so let's start filling it with small humans before we're beyond at-risk age to make them happen and still be in a position to care for them before we get too old. To pop them out used to cost us near nothing, but that changed rapidly in the 90's / aughts and we've been looking at bills north of $3K over the last couple decades. This is a dynamic that's not unique to just child birth. Inflation has been a nation wide issue for 3 years, but it's been a burden on young families for 2-3 decades, which coincides with when birth rates started their downward trend. There are many...many items to cite, but child care hovers above all. Eval metrics are all over the place, but it's safe to say this has increased at least more than double the inflation rate. And it's far from the only child care related cost that has incurred such a hike.
Oh, I have to save for their inflated higher ed so they don't have to repeat what we went through? Oh vey...
I could keep going, but most of those that saw this wall of text but decided to read anyway probably gave up by now. We need more in the trades that require less up front investment, but they also have shorter shelf lives as their bodies break down at a younger age. I also get that what I painted did not capture any spikes in salary, but not everyone is a specialist nor are they a manager / exec. We represent a relatively small piece of the american pie. Are the paths to raising a family limited to the affluent and irresponsible? Sure seems that way. Because the entry point to home ownership is over-burdensome and even if cleared it only gets harder with kids. It was one thing when 'harder' meant responsibilities, but now you have career wives combined with budget crippling expenses and by the time many are in a position to consider having kids they're nearing too old. And looking at our decision makers continuing to pump earnings to the wealthy while the gap widens. They saw opportunities to funnel the dollars up, did, and are bringing back the same old playbook every election cycle with no end in sight.
Are some bypassing children for their own self interests? declining religious affiliation? Of course, but it's a mistake to assume that's the root cause. It's right in front of us.