The sort of people who hang out on r/antiwork aren't getting paid time off even for Christmas. They certainly aren't going to get 20 days of paid time off, plus the existing holidays.
For them, would it be a solution to mental health, or would it aggravate even more when it makes it more difficult to make rent? That is, supposing their jobs just don't work through anyway. I suppose legislation could mandate the day off work, but this isn't a net win at all... then they tweak their hiring practices so as to avoid paying this. More part-time workers who are schedule off that entire week/month so as to not be paid for the day off either. In extreme cases, just hiring fewer workers still, skeleton crews, throughout the year, such that payroll stays the same, but that those who still retain a job are more overworked for it than when they didn't have these extra holidays. Is that net gain on any of a) paychecks for those still working b) rest for those still working c) total paycheck across the entire workforce?
I mean, I think this really does increase time off for some large fraction of the workforce, but not in the way that the OP intends.