These days, whenever I ask a history-of question, next minute I find Gallifreyan (and always Gallifreyan :)) has added the science-fiction-genre tag. A quick glance at the science-fiction-genre tag shows that it is always there on history-of questions.
Do we really need such redundancy?
Genre tags are generally accepted, as we do ask questions specifically about those genres using the tags alone, history-of (which was merged with origins), trope, inspiration and others.
We also have a number of other genre tags:
The thing is to be careful with them, and to make sure the question is actually about the genre as a whole. They're not used to just classify a question such as story-identification + science-fiction-genre, because that's not particularly notable. The sub-genres I listed above get used with story-identification because that is notable, and helps in both finding the questions and researching answers. A parallel is how we use author tags only when the question is about the author, not just about something that the author wrote.
If that's the case, then it should be applied. If it's not, it should be removed.
Also, to address another user consistently editing your question's, you may find that I'd do the same to Marvel questions that lacked marvel. Some users just watch different tags than others, depending on their interests.
They are not redundant.
Just a quick search shows that there are 75 questions with science-fiction-genre but without history-of.
Another search shows that there are 119 questions with fantasy-genre but without history-of
Let's look at usage guidance for all three tags:
Used for questions on the science fiction genre itself, including its tropes and conventions. Should not be used to categorize questions about specific works of science fiction.
Used for questions on the fantasy genre itself, including its tropes and conventions. Should not be used to categorize questions about specific works of Fantasy.
Use this tag for questions about the history of the genre: the origin and evolution of ideas in speculative fiction. Example topics include the first work of speculative fiction with a particular property, or the origin of a term or trope.
It doesn't look like we can do without any of those three tags: each describes a specific area, and they aren't really interchangeable. One can (sure, why not?)
have a question about the science fiction genre without the history-of tag, but it is not hard to see that history-of adds a specific description of the question - that the question is interested in the history of the genre, not tropes or conventions (hard to draw a line, I admit).
On the other hand, purging the genre tags will certainly leave those ~200 questions orphaned - they will have history-of, but history of what? It looks to me like those three tags were specifically created to work together, and it looks like they're doing a good job.
Sure, there is always a chance that some of those questions are wrongly tagged, and in fact don't need some of the tags they have, but I find those sample sizes too large to be easily changed by a few mistags.
There's little chance they'll be used wrongly (I ocasionally see them in first post story-ID questions, but it's not a big deal) since they're no ambiguous - at least they have a tag excerpt that tells you where you do use them and where you don't.
science-fictionandfantasyare banned, and you can't append them to questions. I think it's for a good reason.