I say that this kind of question is acceptable as long rules are met. I try to word the rules in the rest of my answer, but they are a proposal and open to editing or being ignored for a different set of rules.
I say the question has to be about one photo, painting or some such.
The picture should be of a building or landscape feature which is (likely to be) unique and should be main feature of the picture, not an accidental backdrop.
Additional pictures of the same object or location are acceptable.
And the feature should be unique, so not one photo of 'a house' or 'a mountain meadow' in an area where you can expect there to be many of those.
Many of the 'Where on earth' questions are unique and may not meet any rules, but if they are about a feature which is likely to be unique or at least stands out, they should be acceptable.
Use for others than OP is likely to be little in most of these questions, but if the photo is of such nature that the result does not add to general knowledge, that is an extra reason to close-vote.
When a question does not meet the rules we come to agree on here or elsewhere, a close vote (with a link to the rules) should be the norm. But if someone can identify, a re-open request should also be the norm, so an answer can be posted.
One reason to accept this kind of questions is that the community on TSE seems to like them in general (if they have enough quality) as a good puzzle. And if I see what kind of picture gets solved, some of us also like to puzzle out some of the poor ones.
One more good reason given to me by a very active Wikipedia editor: "Indentifying"Identifying historical photos for possible use in WP is valuable service."