Huh, interesting. For what it's worth[1], here's how I see the same matters:

[1] Which may not be much; I will in no way be offended if you don't care.

I didn't miss that the person I was replying to said that "used to" is odd and confusing. I wasn't arguing that "used to" isn't odd (still less that it isn't confusing for novice English-speakers -- it certainly is).

I was arguing that it's a different kind of odd from e.g. "at trække vejret" in Danish, and (to me, but evidently not to you!) I think it's an interestingly different kind of odd, which is why I thought it was worth pointing out.

I wasn't attempting to "explain what it means", which obviously the person I was replying to already knows. I was attempting to explain why it means what it does.

(In particular, it isn't true that "used to" has no inherent meaning[2]. It really is a past tense of "use", and while the specific meaning it's a past tense of is largely dead you can still, if you squint at it, see how it's of a piece with the other meanings of "use".)

[2] Except in so far as no word has inherent meaning.

Evidently, none of that came across the way I intended (or, perhaps, it came across fine but I misjudged how interested anyone else might be in the history): I should probably either have been more explicit or not bothered at all :-).