The "consumer welfare standard" is a relatively recent thing, as the article points out, and there were antitrust actions (e.g. blocking of mergers) that were sustained without direct evidence of consumer prices going up as a result prior to that standard being enshrined.

And many people don't think it's a valid standard. So you might be correct in that this is currently legal - or, perhaps, unenforceable because there's no way to prove that it is illegal to the requisite standard of proof. But if so, then to me that would be yet another argument in favor of getting back to antitrust that we used to have before it got Borked [1], since what we have right now is very clearly not working.

[1] https://www.theamericanconservative.com/articles/robert-bork...