It varies by company. Accrued PTO is carried on the balance sheet as a liability, since it's owned to employees and would generally have to be paid out in cash if the employee is terminated. Reducing that liability makes several financial metrics look better. Some companies shut down for a week and require employees to use up their accrued PTO (or take unpaid leave). Other companies give it "free" essentially as company holidays. There's no right or wrong here, it's just one of many factors you have to consider when deciding where to work.

Worked at a company that would do that (using PTO or unpaid) with a couple months notice.. really messes with any vacation plans you might have made before you've been there long enough to accrue significant PTO!