My personal opinion: I would like to be able to take questions like this, but it would be an exception to an existing policy, so we might have to err on the side of considering them off-topic for now.
It's definitely under the general umbrella of "what to make with X" and non-specific recipe/dish requests (not necessarily specific recipes, but general "what should I make?"), and those have long been off-topic. We deemed those off-topic because they're generally broad, they solicit ideas and brainstorming rather than answers per se.
It does also place some restrictions - preserving, not just something made with bananas, and is ideally asking for categories (i.e. "jam" not jam recipes).
So if we want to allow this question and others like it, we'd need to know a few things:
- how are we going to judge whether a question is specific enough?
- how are we going to keep people from just brainstorming recipes anyway?
(as a mod I care a lot about this, because I have to deal with deleting answers if they veer toward that)
- does this extend to asking for categories of dishes, e.g. sufficiently specific requests for baked goods with bananas?
We also have to consider whether it's worth it. As Erica mentioned in a comment, creating exceptions to general rules is confusing and often leads to debates and bad feelings. Would we gain enough good questions to make up for the trouble?
Quite honestly, I don't have good enough answers to any of this to be ready to make an exception to our current policies and deal with all the debates. I'd be happy to be proven wrong, though.