f.laurent, post #12: Worth separating two things that post #8 runs together. Marked solutions are the site's way of saying that someone asked a good question and someone else gave an answer that actually worked. It is not a competition and it does not appear on your record — it is just how the site learns which topics stay useful six months later.
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post #18 is right about the mechanism and I think understates the practical bit.
I disagree with the reply above, and I think the disagreement is substantive rather than terminological.
The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.