can't we create architectural drawings by only using HTML?

Question

Drawings with HTML

Answer 1

What do you mean by architectural designs?
And by "only" html? Don't you want CSS? and/or Javascript ?

Html and Css are pretty inseparables and you can do a lot with this couple, when with JS in addition you can do almost all, and is required if you want do deal with dynamic... Also, this workflow is adapted for web app ( ie: which run in an internet navigator ). If your goal is efficacity and no need of web app advantages, you'll must consider another workflow not based on Html ^^

Answer 2

if you want to use html5 canvas and WebGl and build some complex drawings there are some great javascript librairies for that, like pixijs.