Au contraire. The REPL is a development environment.
You beat me to it! Yes the REPL is an IDE. That's one of Lisp's and Scheme's fundamental principles. Of course it is not a full-feature IDE like Jedi, but still you can get a whole lot of work done at the REPL.
Don't mix up different levels. REPL is «read eval print loop» that's it. IDE is an environment that can include fancy stuff such as documentation, xref and things I've mentioned before. Yes, repl can be (and should be) underlying level of IDE which even can be just a command line interface over repl. But IDE should be a separate entity either a library or an application.
So even though a full-feature IDE will have a documentation browser, with obviously many fancy features for browsing documentation, there is also a need for the REPL to access the documentation.
Where is a reason to include that functionality right into REPL? If one need such thing he can always use external library for it.
What is important is that hooks in the REPL implementation are available to integrate with the full-feature IDE if/ when there is one.
Also, I don't see any reason for such hooks. IDE must work with object->documentation relations.
Bloat is not only huge amounts of code, but also an assignment of additional functionality to facilities without strong reason, a violation of Occam's razor principle.