To understand much of our language, Gnorts would have to already be aware that our words and symbols gain meaning from how they're used, and you couldn't, for instance, determine that a swastika is offensive (in the west) by its shape alone.
In this case, the term "colored people" gained racist connotations from its history of being used for discrimination and segregation - and avoiding it for that reason is the primary principle at play. There's also the secondary/less universal principle of preferring "person-first language".
This passive phrasing implies a kind of universal consensus or collective decision-making process that the word has officially changed connotation. If this were the case, it would not be such a problem.
What happens in practice is that a small minority of people decide that a certain word has bad connotations. These people decide that it no longer matters what the previous connotation was, nor the speaker's intention in uttering it, it is now off-limits and subject to correction when used. People pressure others to conform, in varying degrees of politeness -- anything from a well-intentioned and friendly FYI to a public and aggressive dressing down -- and therefore the stigma surrounding the word spreads.
It's hard to believe that this terminology treadmill genuinely helps anyone, as people are perfectly capable of divining intent when they really want to (nobody is accusing the NAACP of favoring discrimination and segregation).
Add to this that the favored terms of the treadmill creators don't necessarily even reflect what the groups in question actually want. Indigenous Americans generally prefer being called Indian, not Native American (CGP Grey made a whole video about this: https://www.youtube.com/watch?v=kh88fVP2FWQ).
So that momentary pause you feel when you almost say "Indian" and then correct it to "Native American", who is that actually serving? It's not the people in question. It's a different set of people, a set of people who have gained the cultural power to stigmatize words based on their own personal beliefs.
You're advocating for people to be described in whatever term they prefer and not have a term imposed upon them from outside.
That alien visiting for mars would think "Oh, this is this wokeness I have heard of, respecting groups desires to be addressed in their preferred way".
But no, you're only bringing this up because you believe the people you think are "woke" are imposing a name on these groups from the outside.
Is it a principle or is it a pointless gotcha? I would argue this is aggressively performative anti-wokeness!
The issue comes when you are compelled by your company/social circle/etc. to put your own pronouns in your bio (signalling fake political allegiance), being fired for accidentally misgendering a (badly passing) trans-woman, and so on.
And whether you agree with it or not, there are numerous documented cases online where people were fired for misgendering someone.