Yeah. I don't understand why modern browsers don't allow disabling tabs. I already have a window manager that's quite good at managing windows. I don't need another level for that with its own rules.
It doesn't work well enough. It's mostly terrible, for example window size and position not being remembered, and opening in random places and sizes.
For Firefox, I've found an extension that moves tabs to a new window. It mostly works, but there are rough edges. I apparently have enough resources for all my browser windows in my shaggy laptop for it to never swap. The overhead doesn't seem huge enough to warrant the removal of the possibility of disabling tabs.