I know this is oft repeated but I feel like, at the very least, it needs to be expounded upon. I feel like this statement can be broken up into two pieces. One, the stock market doesn't equal the economy in the sense that small businesses and startups aren't represented in it. In the simple example, as local restaurants close, Olive Garden can benefit from it. But that just means a shift in market share, in what would seemingly be a smaller pie. But that doesn't seem to be enough to justify the current moves.
The other side, which my mind always goes to, is that the stock market can dislocate from the economy. This can be due to technicals, like the Fed pumping the system full of cash as well as the forward looking nature of the stock market. I'm sure there are many other reasons.
I suppose it's impossible to ascribe how much is do to the former or the latter. But the latter is transitory. Obviously, it can last a while but eventually fundamentals catch up with the markets (unless we're in a new paradigm with the Fed). So while I don't doubt the market will get a bigger pie of the economy, the question remains, how much did that pie shrink and will the out-sized gains offset the shrunken pie?