Even before COVID all my collaboration with teammates was done online. (We use Teams now) I'm at the main site for my company; my boss and all my close collaborators are at a satellite location that's not within driving distance; my boss's boss is down the hall from me.
For me, the act of leaving the office at the end of the day is an effective "off switch" that I don't have while my work station and my gaming station is the same chair in the same room. And the office is an effective procrastination temptation blocker that I don't have when I'm at home and surrounded by all my toys, dirty dishes in the sink, and dirty cloths in the hamper.
WFH is the worst case scenario of "taking work home with you", which really isn't the way I want to live my life.
It never had anything to do with collaboration.