Vladimir Kramnik agrees with your observations about chesscom.
chess.com confirmed the issue.
Carlsen, Nakamura and chess.com itself have participated in the Niemann witch hunt. No evidence of over-the-board cheating has ever been provided.
None of the accusers is banned.
Kramnik did the same as they did (by indeed going too far).
It is actually perfectly fine to not ban people doing something wrong one or two times while banning people doing that exact thing for fifth time.
The former is always excused, presumably because people's ancient group instincts kick in. The latter is a single heretic that must be destroyed.
The group does much more damage than the individual. Everyone already thought that Kramnik's pseudo-mathematical evidence was garbage, so why the ban? The answer is that he mentioned well connected people like Nakamura, so the rogue nail needed to be hammered in.
Groups are never punished, and 95% of Internet commenters always excuse the group.
Niemann was already an admitted cheater who had been previously sanctioned for his activities. Carlsen’s accusations against him may have been unfounded for the specific game in question but Niemann’s reputation was already blemished. Niemann’s lawsuit was inexcusable though, as it was essentially a SLAPP [1] designed to hinder everyone’s efforts to get cheating out of chess. Thankfully the lawsuit was unsuccessful and Niemann continues to play chess.
[1] https://en.wikipedia.org/wiki/Strategic_lawsuit_against_publ...