Comment by lynx97
"Ghetto systems" as the saying goes aren't a solution either. Those have been tried decades ago. Remember "IBM Homepage reader"? No? Probably before your time. Its a nice idea, in isolation. However, the translation layers you talk about are never going to be sufficient. You're just moving the problem. Now, if you want to use a system which doesn't have a translation layer for your ghetto system, you're out of luck again.
One of the translation layers can be to-spec WAI-ARIA: then anyone who can be bothered to implement their websites correctly will. (There are currently no correct implementations of WAI-ARIA: only vague approximations of partial implementations.) I don't think there's a way to salvage untagged PDF forms, except taking them case-by-case.
You're right to point out issues with "ghetto systems" – but we don't have a single computer system that actually works, and everything that does exist has fundamental design flaws that make accessibility prohibitively difficult. (Wayland somehow managed to be a downgrade from X11, which is quite a feat.)
I think a basic ghetto system with a full development environment and easily-accessible documentation would rapidly become not a ghetto system.