You're 100% correct. Except neither Google nor Yahoo have yet to figure out how to get people to give them the amount of personal information that Facebook has and does.

I don't trust Google or Yahoo any more than I trust Facebook but at least the former two companies don't know about me what Facebook probably does. I say probably because I actually deleted my account several years ago and block their trackers. But I'm under no delusion that they don't know who I am or don't still retain a significant amount of my personal information even though I deleted my account.