Right, I agree. I like a framework that tries to be a generic web framework for most people who want to write a typical web application in Python. That seems adequately specific to me. I don't consider that "opinionated design", it's simply identifying a market.

"Opinionated design" is an excuse to make interopability and cross-compatibility difficult. There are, generally speaking, few good reasons to do this. Things that are totally out of scope obviously shouldn't be integrated, but if you feel the need to bundle a certain type of library with your framework, shouldn't it be sensible that someone might want to tweak that someday, or replace it with another library that does the same thing in a different way? Opinionated design is about copping out of that logic and putting a smooth sheen on it, it's saying "OK, we understand this is a reasonable, in-scope requirement, but we're opinionated and cool, like Steve Jobs, so we're just going to say you have to use this library or you're SOL. Remember, we are cool like Apple, and that's why we can tell you off in this fashion". Not "only projects that implement this prudent, adaptive, and objectively important-for-our-use-case protocol will work", but "only this library" or "only this way".

Projects that don't suffer from scope creep or far-fetched, irrelevant integration aren't called "opinionated design", they're simply called "well-managed". It doesn't come from having an opinion and telling everyone else to shove it. It comes from having goals and the discipline, reason, and structure in place to stick to them.