This recent question: In Scandinavia, was there a cultural continuity from Goths to Vikings or were they two different groups of people? was tagged as vikings, which reads:
For questions about the Scandinavian seafaring raiders and traders of the 8th--11th centuries AD, as well as about their home culture.
So, the OP was immediately reminded (in a very polite way, of course) that his question was not about vikings, because the vikings were the raiders and they came from several different cultures.
So, the tag vikings is on-topic (by its own description) in questions that are not about vikings, and in which mentions to vikings prompt a correction by the public. Mmmm... that does not sound very "user friendly".
Maybe it would be interesting to remove the part about the "home culture" and explain instead that question about their different home cultures should be tagged, let's say, scandinavia or even (to be created) medieval-scandinavia?