Second, I do think you have a point. To some degree these kinds of tactics have been employed before, but a) perhaps not as maliciously as this time, and b) I believe the landscape of 'influence' changed with the arrival of phenomena like Facebook as mobile phones, and perhaps it just took a while to properly 'weaponise' them.
On the one hand, I feel that this whole kerfuffle is a bit too hysterical considering, as you say, these companies existed before 2016. But on the other hand, many people worried about these things before and it's only now that the concerns are getting (hopefully) the attention they deserve. That's a good thing.
So while I think you have a point, ultimately I don't agree with your conclusion. I do not think it was 'just' that people didn't like Hillary and somehow happened to choose against their own interest.