To quote Xanathar's:
"ARE MAGIC ITEMS NECESSARY IN A CAMPAIGN ? The D&D game is built on the assumption that magic items appear sporadically and that they are always a boon, unless an item bears a curse. Characters and monsters are built to face each other without the help of magic items, which means that having a magic item always makes a character more powerful or versatile than a generic character of the same level. As DM, you never have to worry about awarding magic items just so the characters can keep up with the campaign's threats. Magic items are truly prizes. Are they useful? Absolutely. Are they necessary? No."
It then goes on to say (which is what I've been saying all along): "Magic items can go from nice to necessary in the rare group that has no spellcasters, no monk, and no PCs capable of casting magic weapon. Having no magic makes it extremely difficult for a party to overcome monsters that have resistances or immunity to nonmagical damage. In such a game, you'll want to be generous with magic weapons or else avoid using such monsters."
Now I don't know what kind of evidence is needed, but here are a few things that are true:
Magic items aren't in the PHB, which has "everything you need to play the game" (Maxperson would say anything not in the PHB isn't RAW because of this claim).
Magic items are in the DMG, and never states whether they are necessary or not. Since most of the rules in the DMG are optional, a perception that magic items are, much like Feats, Multiclassing, or Oathbreaker Paladins arises.
There are several DM's you'll find on this forum who prefer a low/no magic D&D for whatever reason, and they will make the claim you don't need magic items, or even spellcasters for the game to run just fine. If you haven't seen any of their posts, I can only assume you have them blocked.
There is no rhyme or reason to how magic items become available, if at all. This is important because while the game assumes they appear "sporadically", it's only as a bonus, not to shore up critical weaknesses of characters. Not every character is going to get an item that gives them a bonus on saving throws, for example. While the PHB does advise that you have a balanced party (kinda), it's in an odd place and not really upfront about it. This led other people to assume the game runs just fine regardless of party choice (something I erroneously picked up on from other people saying- and I'm not the only one).
Because there are DM's who believe that magic items aren't needed (and will say as much quite often to anyone who will listen), that's just another way the game isn't played according to WotC's expectations. This isn't helped by the fact that they are very careful not to say "yes, you really should let players access ABC items and levels XYZ" (see bolded statement above).
The thread says there's a passive aggressive effort to remove magic items from the game- this is false, but WotC is being quite passive about advocating for their use, to the point that those who refuse to believe they should be a part of the game will ignore the few times they do mention you should take them into account (second quote, above).
So I will amend the OP's statement a bit. WotC really should become more aggressive about the expectations and handling of magic items in 2024.