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No, it is not true. People just use what they prefer most. The definition of IDE is also a bit weak. On Linux, many text editors are very powerful, for example Emacs. You could perhaps call that text editor already an IDE. Though, to point out a difference, Emacs (and other text editors) were originally made to be very general and write just anything with it, and handy tools/functions for developing C/C++/whatever were added later. And their programming language support mostly* only covers syntax highlighting, not much more.
Applications like KDevelop or Eclipse were initially developed to be a development environment and most of these still have more/better functionality to develop. I call these IDEs.
There are many different IDEs on Linux, some more powerful, some less powerful, some for one specific programming language, some for many different. Depending what language you want to write in, some are better than others.
Also, some are more bloated than others. That is one of the main reasons people just use a text editor because it is very snappy, very stable and very fast.
I'll list some IDEs which I think are the best in term of functionality specific to that language (like code completion and many other stuff).
For C/C++:
KDevelop
For what I know there is no IDE which has better support for C/C++. I didn't found any other tool which handles C++ in such a way that it really understands STL, which is important that you can use autocompletion for STL containers and such stuff. It even understands macros, so autocompletion even works in very complicated cases with many macro-tricks. I work on a ~250k loc C++ project and it has understood the full code. (To use the extended C/C++ support though, you have to activate it in project settings, it is disabled by default. Also, to have full STL support, I preparsed the STL headers and added that to the C++ support in project settings manually. Don't know