I don't look at it that way. If you have accrued vacation, you "earned" your vacation and they can't take it away from you without compensation. Thus, you are guaranteed your days off. If they fire you, they should even have to pay you your salary for those vacation days.
"Unlimited" vacation just gives all the control to your employer: the right to deny you vacation, the right to dictate how long your vacation is, etc.
This is indeed the law in Israel. What happens is that people are allowed to accrue a number of vacation days up to a limit, typically however many days of vacation you earn in a year, times two. Then the company forces you to take, at the end of the year, a number of vacation days down to the limit.
Companies where this limit wasn't put in place introduced a moral hazard, whereby people would wink-and-handshake with their superiors when they would take a reasonable amount of vacation without actually reporting the vacation days to HR, wherein HR didn't really have the means to detect and enforce against the fraud. Thus people would work for decades, retire, and take compensation for decades of "untaken" vacation days, on top of the normal retirement packages. These policies represented usually $1+ million in obligation per worker and thus were clearly unsustainable without some kind of enforceable limit.
This is required in the US. That's the point of unlimited vacation - since it doesn't accrue, the company doesn't have to pay it out when you leave.
This is the law in California but not most other states.
In most states, vacation time is a benefit that can expire, evaporate, or be rescinded. The company is just deciding not to assign you job duties during your time off. How generous of them! But it's totally their right to decide not to do that, or to put a bunch of boxes around how they will do that. So it's legal, and common, that unused vacation time will actually be lost.
In CA, accrued vacation time is classified as "deferred compensation." It is legally money that is owed to you. It will be paid at a later date, but it must be paid.
It strikes me as no coincidence that the "unlimited vacation" fad started in tech companies with a large chunk of their workforce in California.
Someone I know who retired from a fairly senior position at Netflix rather liked it and took some fairly long vacations but said there really was a good tradition of umplugging at least as he observed that came from the top.
https://namely.com/blog/minimum-pto-what-is-it-why-you-shoul...
They don't do that for normal PTO but it's certainly feasible.
Pretty much no one (outside of maybe something regulated who may mandate two week PTOs for security purposes) is going to do that every time an employee takes PTO. In any case, if I really want to do work I don't even need access to my employer's computers.
Getting sick was jokingly referred to as a firing offense, though people did take sick leave. Burnout was a real thing – and I barely lasted a year, though that may well have been unrelated.
I could easily see a requirement from high up managment to “reduce risk” by having a department have a plan for an unusually long holiday stint (I.e someone taking 6 weeks off in a row), fundamentally because senior management don’t trust middle management.
At the job before that I had accrued 6 weeks of PTO, which was the max. I took every other Friday off after that and was paid out a month and a half when I left the company. Everyone understood the situation, so it wasn’t looked down upon when I was gone every other week.
My perspective was that unlimited PTO was a scam to reduce vacation time. Most people are not going to take advantage of it, so the company benefits.
What unlimited means is "as long as your manager is decent, you will maybe get your days off" vs accrued vacation where you may be forced to take vacation to not lose it.