[ghaff]

PTO balances are typically still liabilities because they're owed to employees when they leave modulo accumulation caps or use it/lose it policies.

It's pretty much inevitable that pooling sick time and vacation time results in a lower total. People aren't really expected to use all their sick time in a given year if ever. But for those who do plan to maximize their use of vacation, it means there's not a lot of margin when they do get sick and it encourages behaviors that aren't good for anyone.

[moron4hire]

Even worse: so-called "unlimited" leave policies. It's basically "no obligation for leave at all". Hence why it's very popular with the startup crowd these days.

[ghaff]

From an accounting perspective, there's also no (or very limited) liability associated with accrued vacation time. (There may be some associated with required sick days.) If someone leaves the company, there's no accrued time to pay off.