Because people will abuse it, which sucks. And if you go with an unlimited PTO option, there’s often a lot of cultural pressure to not take PTO.
so discipline those that abuse it? It’s really a symptom of not engaging with your workforce on a realistic level. Many non-American countries deal with it adequately. In the UK your sick days don’t come out of your vacation, and if you need more than a week off you have to get a doctor’s note.
And whether that’s a good system comes down to the quality of your immediate leadership. PTO gives you essentially a right to use time off for whatever you need, whereas discretionary time off comes down to the discretion of your manager. Some prefer the guarantee over a promise.
I’d argue that “you can use it however you want” is pissing on my boots and telling me it’s raining.
I want to use my vacation for vacation, as it’s vacation. I don’t want to use my vacation for being sick. If it is truly what I want that really matters, then shouldn’t that be respected?