That is an overestimation of the power of subreddits and football forums, Twitter/X/whatever is a lot bigger than any of that and this will not really put a dent in them or Musk, for whom its a money losing vanity project anyway. Journalists for major sports publications like The Athletic aren't going to boycott X because their employers won't want them to sacrifice that kind of reach, so their breaking news will still be there, ergo the readership will still be there. Half of the users on here/those subreddits will just end up using it privately anyways to read the same things they'd have been reading on here.
If it gratifies the majority of the forum to sacrifice a great function of this place so that they can be under the impression that they're doing something of consequence then have at it, I think it will just needlessly take away one of the best things on here, which is people parsing United related news/rumors and giving you good takes on who is and isn't a trustworthy source. If X embeds are gone you will just have people posting second-hand info they read on there anyway, and then people clogging the place up clarifying the source and its reliability without actually being able to just link it.