You have to check Facebook anyway because schools, HOAs, businesses, even local governments often treat it as their primary outlet for information, as in, stuff gets posted there first, and sometimes only there. Though IG is taking over some of that (but of course that's still Facebook)
Luckily my wife does that, so I can get away without having an account, but I'd basically have to have one otherwise. If you've already got one and already have to visit Facebook sometimes, may as well use FB marketplace....