Experience seems to be what's holding him back in this case. I've always done it this way soo... As developers and engineers, we have to be ready to change our assumptions and workflows to adapt to new technology.
We can only say that it's "holding him back" only if we can show that he doesn't get the same results as SASS users, in the same amount of time.
We think your path is the wrong way and will cause you problems as time goes on.