For questions where ownership is a factor: user name in timeline entries, chat pinner, chat room creators, and occasionally when you're a tag creator, etc. and the system differentiates (or should, in the case of a Feature Request) the user based on that fact.
Where being the owner confers privileges (or should but doesn't) and/or requires a visible or functional difference not offered to other users and said ownership isn't so much voluntary but necessary for better or correct function.
Please note: You don't "own" questions or answers, even if you created them; though while for the purposes of the taxonomist badge (create a tag used by 50 questions) the creator is an owner per se the addition of this tag for these voluntary circumstances is superfluous over simply using the tags: questions, answers, or taxonomist. Where someone else selected your answer making you involuntarily the best answer (and one is affected by that) might be an exception, but that doesn't make this a good additional tag for most selected answer questions.
Much like "blame" but with an entirely neutral connotation.
Caution: With infrequently used tags such as this it's best to see its history of use prior to using it on your question, and not adopt prior incorrect usages. If you're not sure you need to use this tag you probably don't, if it's necessary it can be added later.