in C++ the ratio of ppl I know using an IDE with semantic code completion ability (that is, not rtags but actually using e.g. libclang or something that does understand C++ to some extent for IDE completion) vs "glorified text editors" must be 95/100 using an IDE though.
But your assertion is weird. Either you work on Windows where everyone is on Visual Studio, or you have 95/100 people around you using CLion, XCode, and Qt Creator, two of which don't even have an entry on GP's survey link. One of which is probably only used to sign apps for ios. Could you give more info?
TBH, in my limited experience, I have never seen code completion working well on large C++ code bases. I remember years ago VS literally becoming unresponsive when intellisense was enabled.
Notepad++ and vim are the 3rd and 5th most popular development environment according to stack overflows 2019 report [0] and I and many others I know use Vim at least.
> IDE knows types of things, type `myobj.` and you'll get a suggestion list with methods of that class callable from the current context.
I've never used notepad but Vim absolutely supports omni completion [1].
[0]: https://insights.stackoverflow.com/survey/2019
[1]: https://vim.fandom.com/wiki/Omni_completion