Why do companies do return for office when it will make them lose staff?

I’ve been remote since 2020 March and we’ve now been told to go back into office. I’m annoyed because even within a very uncertain landscape for the company I’ve worked for I’ve managed to secure high raises even in years where that’s been rare. At times I’ve worked till midnight to get something done because I don’t want to look at it the next day. With return to office, who’s gonna bring work home and open their laptop at home? It makes no sense. Beyond just this annoyance factor though, we have 2 very senior people on our team, one close to retiring and I’m sure this won’t delay them. It seems like even if one begrudgingly accepts going back, what of all the talent you lose? You have to hire new people to replace people who’ve been there some of them for their whole adult careers, who’s going to train the replacements? Who takes on the roles while other people are still learning the job? If you remain the most senior on the team, then it falls on you, but you already have a ton of work to do anyway. It just seems like this is a really bad idea any which way I look at it. I keep thinking maybe they just want to kill the company, but even that is weird, they could just lay people off without severance if they so choose.