I don't think this is a "M$ is teh evil" troll but rather a cultural misunderstanding. In a Linux environment development tools and libraries are naturally considered as part of the OS; under Windows they're normally considered as separate from the OS, so someone coming from a primarily Linux background and working off the assumption that Windows works the same (big mistake guaranteed to create all manner of hilarious - and not so hilarious - misunderstandings, and yes, it also works in the other direction) sees all of these listed as separate programs and jumps to a conclusion (possibly one influenced by the "bloatware" myth too).

In fact Linux can, and does, have the ability to have multiple versions of glibc on the same machine too. See http://stackoverflow.com/questions/847179/multiple-glibc-libraries-on-a-single-host

The key difference is in a question asked above: "this doesn't need a user to install yet another runtime package does it?" - yes, I know the question was about Mingw on Windows, but it shows the root of this misunderstanding. No, it doesn't, because it's already there. If, however, you had a program that required a different version of Mingw, and if there were incompatibilities between the version, then yes, both versions would be needed. Same applies to glibc on Linux (see the SO link I posted above).

There's also another cultural misunderstanding here, whereby on Linux the typical user is a programmer, whereas on Windows the typical user is not. So the typical Windows user will download a program, it will come pre-packaged with the required redistributable components, and everything will install cleanly. So no - on Windows the typical user does not have to install another runtime; the program's installer will do that for them automatically. The typical user does not worry about these things, the typical user gets on with using their computer to be productive in other areas.