Yes, that's what was being said.
But it won't. In vi (and friends), \< is "beginning of word", and \> is "end of word", so \<a\> will not match the a in "absolute" or "tundra" or "fabulous", but will match the a in "(3+a)" and "a=7". Certainly there are text editors that don't let you express this, but they're so broken as to be basically unusable.
An IDE that is able to keep the various references separate is still more powerful, but the difference is tremendously smaller - particularly if you follow the scoping guidance at the root of this comment thread.
Edited to add: Additionally, if your cursor is already on the word in question, that search is one keystroke. * says "search for the word under the cursor" and incorporates the word boundary markers.
That said, this is also where the scope consideration comes into play. If something is used in 100 different lines, 300 lines apart across 3 files, then of course naming it 'a' is crazy. If something is only in scope over 5 or 10 lines, then you simply restrict your search to those lines (either explicitly with marks, line numbers, or pattern bounds; or implicitly by exiting the search when it gets to a region you don't care about - find-and-replace in vim has a "confirm" option).
I think he was contrasting it to an ide that will automatically find out which as "a"s are references to the same. ("Find usages" in most Java ides I think."