As with many other things, it is what you make of it.
So their giving big companies and corporations data?
OMG!! THE HORROR! EVIL CORPORATIONS ARE GOING TO USE MY INFORMATION TO TRY TO SELL ME STUFF!!!11 Being in cahoots with political groups is a little more annoying, but still...
Anonymity in the digital age is going the way of the dodo bird and our concept of privacy isn't going to last either. IMHO, avoidance is going to make it worse. If you aren't using it, someone else might be. I think you're better off if you are in a position to at least manage the information connected to yourself, which means using the platforms.
And, for the record, this is already a problem with businesses. Google, Yelp and others automatically put up profiles for any and all business listings they can get there hands on. Katie has had a hell of a time with Yelp and Facebook, and Google has our business hours listed wrong which has caused several stinks with clients. She can't delete the accounts so the best she can do is manage them, which is a headache, but has to be done.