That's the catch though. If you abuse it, your manager will clearly call you out on it and make it an issue, negative performance reviews, less bonus or raise to make up for the abuse of company time. But if you don't use as much as usual it's not thought twice about or rewarded.
It sounds cool, but in reality the odds are most employees will end up using less PTO than what they originally had.
In the past, with tracked PTO of use it or lose it, a good majority of employees ended up taking off a good portion of December and then there became a staffing issue. The other thing this eliminates is the time and legwork needed to keep track of PTO, payouts, carryovers, etc. for the Accounting Dept. It's kind of like self-checkout in stores...put the onus on the people to be honest and it will ultimately save the company money. Yeah, some will take advantage of it and you'll lose on those few, but majority will either be honest or be better than normal so the ultimate result is money savings.