I don't understand this idea of considering opinions extremist is coming from. I'd say, it's about needs, I think it's either needed and make sense to adopt a kind of tests or not, otherwise I stand by my past questions, if a unit test ensure maintainability etc. of a piece of code, what is the rationale for which it's not needed for a piece of code, if functional tests ensure correctness of behaviours, what's the rationale for which we don't need a functionality / piece of code ensured for correctness? I cover by unit / functional my code bases completely, because I value what they add to an application, and can't think of a piece of code that I don't need to be maintainable or a piece of functionality that doesn't need to be ensured to be functional, is that extremist? It depends on what, in your opinion?

EDIT: I can only think of reasons beyond technical, in case of limited time to market or tight deadlines, but in that case it's tech debt tracked by tickets and docs, still going to be subject to test-writing

Even in ideal conditions, it depends on the project, the language, the methodology, the architecture, on the stance on mocking, on the engineering philosophy used. It depends even on what a person considers a "unit test". For all I know, by "unit test" you might also mean what people call "integration test".