@Mbitr
I have a feeling your case somehow falls under the same category as crackfoo's case and this was mprep's response to that case:

Quote from: mprep on September 13, 2020, 01:14:49 AM

See rule 1:

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1. No zero or low value, pointless or uninteresting posts or threads. [1][e]

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1. Such posts as "SELL SELL SELL", "I agree", "+1", "Support", "Watching", "Interesting", "LOL", "SCAM", "LEGIT", "FAKE", other one word posts, posts consisting mostly of swearing, quote pyramids, useless introduction threads, threads about a topic already recently discussed in several other threads.

You're free to be polite and thank other people in addition to providing something else of substance that would take the post out of the territory of "low value". Not sure why you mentioned the thread being self-moderated since that doesn't change the dynamic here. Self-moderation doesn't override or substitute the rules and standards according to which the forum is moderated by its staff - it's another layer of moderation where the user can also decide which posts can stay and which should be deleted (though he isn't bound by any rules or standards the forum staff are).

Quote from: ranochigo on Today at 08:30:48 AM

I don't think it's particularly fair to remove posts that express gratitude but perhaps giving a merit would be better.

But merit should be given to high-quality posts and such posts are the exact opposite.