> It's actually really hard to know multiple operating systems, windows managers, desktop managers, file systems, package managers, etc. It's really a waste of brain space but a necessary evil. You can still only be an expert in a subset and muddle your way through the rest.

This is incredibly true! I'd argue that even on a given platform, that one only ends up knowing a portion of it!

Heck a part of it is just stuff learned through osmosis. If I'm on Windows I know I can use tools from Sysinternals[0], such as Process Monitor, to save myself hours of time. Put me on *nix and I do not know how to do equivalent system level traces. But I've met many highly experienced cross platform developers who also don't know about Process Monitor, oops!

These platforms have decades of history behind them, a specialist in just one will always know more than a specialist in multiple!

[0]http://technet.microsoft.com/en-US/sysinternals