Also, even what they are describing, the lionizing of ingroup preference, is ideological
I can't say I follow or agree on this point. I think this just the method of practical carrot-and-stick behavior modification. The promises of in-group rewards means even a Jewish person will become a a Nazi, or Candace Owens will become MAGA. Then fear of losing in-group status is what keeps people in line: Carlie Kirk back to toeing the party line over his audience after one phone call.
It's a brutally effective way to prey on people where they're vulnerable: primal fears and desires.
I think ideals do exist, I think "from each according to their ability, to each according to their needs" can only be explained as an ideology because it places an intrinsic value on people, not a practical value. It exists regardless of who the ruling party is.
I never got the sense it was about a sense of universal goodness that exists independently of the ruling party, but because earning approval of the ruling in-group could help you earn carrots and escape sticks.