And of course some asshat downvotes because you bring up ruby...
I'll just point out that rvm isn't a pip for ruby. It only manages what version of ruby you're currently using and allows seamless switching. It comes in handy with ruby because of all the compatibility issues between ruby versions and rails versions. Pip is a sophisticated package manager that can be used with virtualenv to isolate where Python libraries are installed. They are indeed both good tools for development but serve different purposes.
RVM also manages gemsets, which lets you quickly save and switch the set of installed gems (packages). You're correct that it doesn't replace gem as a package manager.
I'll just point out that rvm isn't a pip for ruby. It only manages what version of ruby you're currently using and allows seamless switching. It comes in handy with ruby because of all the compatibility issues between ruby versions and rails versions. Pip is a sophisticated package manager that can be used with virtualenv to isolate where Python libraries are installed. They are indeed both good tools for development but serve different purposes.