The voting patterns on that question indicate general acceptance of the idea that the presence or absence of a formally-accepted answer should not be a requirement for deciding whether a given question should be chosen as the target for a duplicate. However, I am seeking clarification as to group opinion on whether formal acceptance of an answer should nonetheless be considered as a positive marker of quality, to be considered as one factor of many, such that if two answers are otherwise similar (i.e. no major discrepancy in quality by other measures), the one with the formally-accepted answer is preferable.
I know that, in my own experience learning to use the site, I very quickly came to take note of the presence of a formal acceptance, which the site's mechanics seem to encourage by:
- awarding points to the accepter,
- bringing color emphasis to the accepted answer, and
- coloring the vote count icons green for links to those questions on the sidebar (or in other automated question lists).
It certainly seems reasonable to reward even casual/new users who go through the effort to fully participate in the Q&A process by giving some weight to their acceptance when deciding which answer will be the duplicate target and is therefore more likely to get future traffic.
I recognize that many new users do not learn the entire process and don't formally accept good answers, instead announcing via comment or edits that the provided answer is correct. I don't contest the idea that for two questions A (with a weaker answer, formally accepted) and B (with a stronger answer, accepted by comment), B makes sense as the preferable target. But if both A and B have answers of approximately the same strength, doesn't A (the one with the formal acceptance) make a slightly better example after all?