From the employee's side, there's too much risk and uncertainty around PTO when leaving a job. It's easier to just take a vacation before putting in your notice

From the employee's side, there's too much risk and uncertainty around PTO when leaving a job. It's easier to just take a vacation before putting in your notice than to haggle with your employer after the fact, when you have no leverage. This is especially true with companies that offer "unlimited vacation" in which PTO does not accrue.