Not totally true, the real value is combining data from different sources, but since the data they get wont have your email /ip/device/contacts etc it will be a lot harder to harvest usefully for advertising. Maybe they will figure out things to use it, but what they can use is already quite public, so they don't really need to federatie for that
Same holds for YouTube. They just got rid of the only no ads subscription here. Which was half the price of premium. So they kick people out of that, and afterwards going to war with ad blockers... If they really wanted as much people as possible to pay, they would have kept that abbo. But probably it's better for them financially to have a bit more with ad blockers and ads and convert some to the premium tier