who are focused on their camera brand as an identity.

This is exactly it.

My pet theory is that it’s a fairly technical hobby but a fairly difficult art form. You can master focus, exposure, lighting and post-processing and still end up with a very boring photo. Have these technically competent but artistically bereft photos that most viewers just shrug their shoulders at and it drives them insane.

I don’t think this is at all. The bitter conversations almost never show up in discussions about actual photography, with few exceptions it’s always in hardware discussions and boils down to brand loyalty/tribalism.