this is huge flamewar territory, but this is a bit 'off' question wise - alot of the current state of things is due to historical precedent - some details:
- (original) vi was on most unices from the mid-80s onwards out of the box
- (gnu/lucid) emacs was an additional install (not getting into other emacs flavors - original teco emacs was fairly small i believe).
- original vi just had basic editing and at some point a hardcoded lisp mode, no
addons vs gnu emacs which was a programmable editing environment running within a lisp interpreter - remeber in the early days, people built whole custom hardware to be able to run lisp with sufficient complexity (see also: lisp machines, twenex, etc), so using lisp for your editor was in some sense the definition of 'overkill', depending on ones view of what an editor should do
- Also, from late-80s->90s era if you wanted a GUI for your text editor you probably used emacs, and real vi never had a gui option - put another way emacs was the only one of the two linked to gui libraries.
- vim vs vi: most obvious difference (IMHO) feature wise is that vim adds vimscript, which is an interpreted programming language, so now editing modes are extensible, etc (as was the case in emacs before). detail: vim codebase is not based on vi codebase.
since vi was just about everywhere and emacs was a (fairly large) package, you had more general vi knowledge vs emacs 'in the culture' since even an emacs user might need to know vi but not usually the other way around, and so vi (later vim, as linux distros switched their 'default vi' to 'vim') gained more install base by default. Then, people hearing about emacs likely hear the 'vi vs emacs' arguments and never try it since there are now many more choices, they've learned vi, they prefer an IDE, etc (in the old days there was much less choice, main 2 were vi and emacs, and emacs was probably somewhere on your managed LAN somewhere if you wanted to give it a shot)
most of the 'vi vs emacs' arguments are rooted in the real-vi vs fsf-emacs era and are basically obsolete in a modern vim era, since everyone is using gui library vim with vimscript, which basically means the same thing in terms of 'bloat' (both editors contain engines to display text in cli or gui mode and embed a language interpreter). Basically what was once valid internet lore kept getting past down, and the 'minimalism' of vim was confused with being 'minimal' in terms of what people meant in the original vi-vs-emacs discussions. Emacs does contain 'non editor' functions e.g. networking, etc, so the core is probably a bit bigger than the core of vim, but when people are still using these comparisons and talking about 'emacs bloat' while their preferred editor is some electron based thing, we've lost a bit of the point/message..