Because management is going to use their "commitment" to try to make you feel bad for not working harder. (You don't have to accept the guilt package they try to drop on you, of course. But they may also tie things like raises and promotions to it, which is harder to ignore.)
Interesting. In my several decades of working in this industry, I've very rarely seen anyone get meaningful raises anyway. You get a raise by taking a job at another company.
But true, if you're worried about getting promotions, then that's an issue.