Best guess:
As long as they are distinct terms, they satisfy a "not equal" test. Thus, they are different things. If guilt by association where applied to terms, then we'd have a lot more trouble with English than we already do.
juice, e-juice
then, than
e-mai, mail
two, to, too, toot
all have distinct uses, different meanings, and are not the same.
Although both vaping (e-smoking) and smoking inhale (or at least draw into mouth), they are different substances and are not the same thing. You can't call vaping smoking. Neither can you call e-smoking smoking. Smoking requires smoke.
To reitterate...e-smoking and smoking are completely different concepts. The error is in the question:
why is this forum called "General e-smoking discussion" instead of "General vaping discussion"?
Although it could have been caled General Vaping Discussion, it doesn't have to be.
It's like asking "Have you stopped beating your wife?" The error is in the incorrect thought process of the question. (Saying "yes" or "no" is equally bad. A loaded question.)
Although, to be fair, I think I asked the same question long ago. And basically, it's that way for historical reasons and won't change.
However, "e-smoking" does not necessarily imply smoke and is a distinct term with "historical" roots in mannerisms. I think.