lol, I've been a javascript developer (among other things) for over 15 years :)
The point is that some people/teams/environments prefer to not treat everything as a javascript app. Especially in the agency world -- thinking about one's website from a markup/design-first perspective is a totally viable thing. And if you have designers on your team (or for solo practitioners) you sometimes don't want to javascript all the things. It's great that you found an approach that works for you, but it doesn't mean that it's the only best way for everyone and every situation.
The point is that some people/teams/environments prefer to not treat everything as a javascript app. Especially in the agency world -- thinking about one's website from a markup/design-first perspective is a totally viable thing. And if you have designers on your team (or for solo practitioners) you sometimes don't want to javascript all the things. It's great that you found an approach that works for you, but it doesn't mean that it's the only best way for everyone and every situation.