I don’t deal with any business that uses solely facebook as means for communication. I don’t miss them, the platform does a bit less and things get less enshitified. Craigslist isn’t that bad, I still use them all the time, people are much better than the flakes I used to deal with on facebook marketplace. There will be a federated classifieds soon, I’m sure, and the people will regain that corner of the market again.

Unfortunately there’s a lot of things that communicate only via Facebook, and they’ve decimated Craigslist so it’s the only place to sell crap.

Undead marketers?

Sounds like a made up problem!

Even in your example, absolutely no one forced anyone to use it as a "social media" app. If it is a matter of convenience to access the notices, or talk to teacher, then use it like how you would use school/work apps such as canvas/blackboard/slack/teams apps. Stop using it beyond it's purpose. Which is to say, add "friends" if you have to so that you can access notices or messages from your teacher or whatever. But doom scrolling on clickbait and keeping tabs on Exes shouldn't be done.