There have been so, so many attempts to decentralize in my lifetime. I used to be a huge believer and worked on these problems, but have to admit I'm somewhat exhausted. The technology is not the problem. The problem is always quality, effort, and cost.
If decentralization is ever going to win, it needs to be turnkey, explained without showing a network diagram, be basically free to run on your laptop, and actually have the content people want to see and not just be a bunch of people who speak lojban. [1]
While I'm not sure how much of a legal leg X has to stand on, I understand why they'd rather Nitter not exist. Twitter tried (valiantly, imo) to stay open. What ultimately began the API lockdown was the need to stop bleeding financially. Ads were inevitable, and there being no reliable way to do that via API access.
Twitter solved those three problems, and no one spends nearly as much time talking or caring about the technology used to do it than people who talk about decentralization. Myself included in my younger days. Now they're just defending their moat.
1: https://xkcd.com/191/