You caught me: I've not hired a domain expert coder. But I've also not paid $120/hr for front-end coders. I over-paid for one guy who knew far less than I did- horrible coding practice, always thought he was farther along on the project than he really was (and wanted money), and, in fact, never got far enough to even understand the problem before I terminated the agreement.
For $120/hr the person isn't fiddling- they've done it before, probably have a personal library they can pull, and a basic shell of a website can be ready pretty quickly. Their time is almost entirely spent on the custom part of the site.
Still it doesn't necessarily pay. There is a very large productivity gap between different people, for different tasks in software development (in the 1-50x range).
For $120/hr the person isn't fiddling- they've done it before, probably have a personal library they can pull, and a basic shell of a website can be ready pretty quickly. Their time is almost entirely spent on the custom part of the site.