If you want to play 800-level chess, you can have fun without knowing any set openings. Well, almost. You'd better be able to recognize and defend scholar's mate at a bare minimum.

But that is a bit like being an amateur programmer who never learns what a function is. You can still enjoy programming at that level, but it's odd to describe functions as crutches.

Besides, once you get into the middlegame, you still need the tactical and positional skills that I suspect you consider opening knowledge a crutch for

In chess (and life) it’s far easier to pattern match a solution for a position rather than coming up with a brand new solution every time

In my opinion, this makes memory and experience far more important than intellect in chess, especially in the faster time formats

Without opening theory you will just get worse middle game against any competent opponent. Furthermore, if you could just calculate everything ab inito your play would be identical to “memorized opening,” alpha zero did learn a lot of standard openings from self-play (without being shown these opening explicitly). If someone plays a “bad” opening in a serious game it’s because not only they don’t know theory but they also can’t calculate well enough.