News flash: technical worker thinks more resources should be diverted from non-technical matters to technical matters. Film at 11. ;-)
The people who design interfaces and the people who do branding and identity work are rarely the same people. I've done both (and was developer all over the stack for a decade,) but never at the same time. Branding and identity work is usually done by specialized agencies, and they're usually the ones who make decisions about the type stack.
What you and most other developers don't realize is that these things do actually matter— just not in ways that non-designers consciously pick up on. When looking at an individual website, most folks might not see much difference between a poorly kerned system font and a really expensive 'pro' font painstakingly hand kerned over months or years. However, when people are encountering a brand on a whole, having a uniform, polished look across media dramatically affects how it comes across, and that is hugely consequential. Think about how differently car dealership websites land than car manufacturer websites? And they're selling literally the same fucking product! A knowledgeable designer could write an essay on the difference in the two designs while a layperson would likely shrug and say "it looks... smoother I guess?"
It's really no different than performance for developers. Most people don't consciously notice the difference between a website that's really really streamlined and optimized and one that's just kind of okay... But the meh site will not inspire positive feelings about the experience. If your competitors do better, you likely won't be the one getting their business even if the customer didn't consciously reject your business because of it.