I mean, did they steal it? Or did people largely willingly give it away? People willingly left the older decentralized platforms in favor of centralized corporate platforms because, for one reason or another, they felt it was a better use of their time. The old-school forums weren't killed; people stopped using them and left for Reddit and Facebook and Instagram etc.
If we want to reverse this, we need to understand why this happened, what those service provided that lured people, and how we can build better alternatives, and I think there's more to this than just "corporation bad".
Edit: Downvote if you like, but I'd much prefer an actual response, because I think there is an interesting conversation to be had about this.