Imagine an established user accidentally makes a post through a new or unregistered account (or intentionally to prevent their account credentials from being compromised through a public network). That post will then show as having come from a "new contributor", but once that account gets merged into their main one, the post will still show as "new contributor" even though it will appear to have been posted by the established user.
Recently, a situation happened where a completely new user posted a question, and as such, it got the new contributor indicator. That account was later merged* into that of a very established user and moderator of the site. This caused a lot of confusion as a moderator was marked with the indicator.
This happened because the indicator is attached to the post, not the user; as the post met the criteria for adding the
OwnerIsNewPoster internal mark that causes the indicator to show if the post is less than a week old (among other things), it showed the indicator.
Ideally, this situation would have been resolved if the indicator would be attached to the user and calculated on the fly as needed, rather than the current (IMO weird) way of attaching the mark to the post, but that seems too technically difficult. If we're insistent on keeping the current system, can we please recalculate the new contributor indicator on a user's posts upon their account being merged into another as if the posts were made through the parent account in the first place, and remove indicators that wouldn't have been applied in that case?
* Their post was actually manually reattributed, but this does happen on merges, and I want to refer more to the general case rather than this specific case.