You don't owe anyone a follow (this includes me). Not even people you've been mutuals for a while. Not even people you know on real life. Not even people whose profile you check often. Sometimes they just post too much. Or post stuff you don't want pop up on your list (but want to check on your terms). Or they start (re-)posting hate (you don't owe them a call out; especially not if you don't think it will go well). Sometimes they are lovely folks but just bore you with their favorite sports.