My guess: it is a low hanging fruit and then they can say "Look! We blocked X million bots! So you can trust the users that are left...... please don't look into it any more"

because people used to do this all the time with ads: serve up an ad click, get paid… so spin up a bunch of clients and have them click ads on your site, easy money!

shareholders want real users, not bots. Facebook has to tell shareholders that real eyeballs are looking at ads, not virtual ones. Facebook is an adtech company—all tech they develop further establishes their advertisement empire, if advertisers (or more specifically, investors) find out ads on facebook aren't worth their value, then facebook dies.

Pretty sure they only care because they could get in trouble for shareholder faud