There is a difference between a question that could be answered on another site, and a question which is off-topic for this site.
For instance, I'm probably going to start asking questions about Go Boxes, some of which will involve mostly power source issues.
These questions are not off-topic for this site, if they have to do with Amateur Radio, they should stay even if the question could be moved without change to another site and still receive an answer. I don't want to add an addendum to each question indicating that while it could be answered elsewhere, there are issues and products specific to this community that might resolve it better than the other site would given that it's for ham radio use.
The sites can overlap, this is OK and by design.
So please consider carefully whether the question actually doesn't belong on this site at all before suggesting it be migrated to another site when there is obvious overlap.