While reviewing Most painful way to kill somebody with 10 bullets? I looked up the torture and execution tags. Their definitions aren't great in context of worldbuilding, and I think that's encouraging people to slip non-worldbuilding questions into the queue.
The more egregiously abused of the two is execution. A review of the questions using the tag shows that 75% of the questions (9 of 12) have negative votes and 33% (4 of 12) were closed. That strongly suggests to me that the community's belief that execution questions are off-topic.
To be fair...
I think there could be a place for the execution (and similarly torture tag, although its percentages are not as high) tag within a world-building context. In other words, if we changed the tag's description from:
The deliberate killing of an individual in a controlled environment and its methods and ethics.
to something like...
The political, social, or technological considerations involving the sanctioned and deliberate killing of an individual in a controlled environment.
...(Although I'm not completely happy even with that)...
we might get fewer abuses of the tag. Maybe. I'm not convinced a lot of people read the tag descriptions before applying a tag.
Anyway...
The execution tag doesn't get a lot of use, and what use it gets is predominantly down-voted by the community, which suggests the tag should be dropped.
An upvote to this question is IN FAVOR of DELETING the tag
If, on the other hand, you're in favor of keeping the tag, please consider posting an answer that explains how the tag description & wiki can be updated to better focus users on worldbuilding rather than storybuilding.