your phone can’t work if your carrier doesn’t know where you are

on top of that, advertisers put bluetooth receivers everywhere, which will log your phone as having been nearby, even if you don’t connect

on top of that, you can do the same bluetooth trick with wifi endpoints

plus your phone has a gps/glonass/whatever receiver in it

probably other reasons too but those are the ones i can think of off the top of my head

yes you can maybe mitigate all of these, but there are probably ones i haven’t thought of that people much smarter than me have, so why take the risk?