HTML is much more basic than programming it's basically english in brackets.
Also if you can find me a "programmer" who doesn't know how to use HTML then you have found some very awkward person.
We're aiming Forge at people who can't code their own website from scratch, not really you or me. These non-techies can manage a Wordpress install or a Squarespace site, and just want to sell something online.
I think that selling online shouldn't be about the logistics of running a website and handling payments. It's more of a product and marketing problem. Forge takes away some (but not all) of the technical hurdles of selling things online.