the "betrayal" is supposed to refer to Fallout, which began as a 90s RPG from the same company as Baldur's Gate and Planescape: Torment, but is now an idle clicker game
it was a slow slide from turn-based combat RPG to bullet-time FPS to get there though. and New Vegas was good!!
and so was NuCom 2! it was legitimately good!
but when you look back at Fallout, and then look at the next step XCOM is taking, you can't be optimistic for the direction that the IP owners are going with it.
That doesn't really seem to be the case, though.
With Fallout, Fallout Shelter is still pretty straightforward and not really a betrayal.
It was announced at the same time and place as Fallout 4. Fallout 4 is a pretty consistent progression of Fallout 3. So bar the huge shift in the series from Bethesda starting work on the IP, there's not much going on here. Fallout Shelter existed, and did not change the direction of the series. There's the whole thing with Fallout 76, but it is no way a progression indicated by Fallout Shelter.
But regardless. XCOM2 doesn't represent any kind of simplification of XCOM 2012. Hell, with the DLC included (and compared to Enemy Within to be fair) it's
more complex. Especially the fatigue system. A mechanic, added in the mainline expansion pack to XCOM2, that
increases the size of your roster therefore allowing permadeath to become a bigger factor in the game without effectively translating to a game over. When you lose a character, it's a lot easier to continue as a player when they were 1 of 16 then if they were 1 of 8. So for more people, permadeath becomes a more prominent feature rather than a fancy way of telling the player to restart or load their prior saves now.
Chimera Squad is A.) clearly developed by a smaller team as part of a smaller project and therefore does not represent significant investment in some "new future" of the series. It is B.) Not emphasized by Firaxis, being $10 and releasing only 9 days after its announcement and reveal. It C.) is pretty clear in why it has the features it has. It, this specific one-off game, wants to focus on set characters as soldiers you control. It is not a good idea to try writing important characters around permadeath in any scope unless you're fine with just telling the player "okay you fucked up your save now that they're dead good luck". So no permadeath in this specific, one-off, game.
For a $10 game, it's clearly presented as "hey, we quickly made a small campaign focusing mostly on tactics and story! Like the combat in XCom2? You'll like this!" The features that aren't included from XCom2 aren't missing because they're considered not part of the series or not beneficial overall anymore, but they aren't included because they're out of scope for a $10/$20 game.
Using the Far Cry example, it's like looking at Blood Dragon and deciding that it
obviously means every Far Cry game in the future will, without exception, be shlocky 80's B-Movie sci-fi because since this small-scope spinoff clearly can and should be used to determine the future of the whole franchise.