Compared to writing an application for Windows, yeah, writing an application for Linux is really easy. All you have to do is GPL it and make it attractive enough that users want it -- and presto! -- the distribution's people do the hard work for you, and they'll even help you figure out difficult things like processor optimization flags and so on. Sure, sometimes mistakes are made, like when a certain distribution compiles my app against a different version of llvm than their graphics driver, but that's kind of a given: mistakes will be made.
On Windows, on the other hand... There's the endless plethora of varieties of Windows, xp, vista, 7, 8 -- with the various service packs, but even with the various sets of patches: on some versions of Windows 7 with some set of security patches, installing an application while Windows checks for updates will make sure the install half-fails: the app will refuse to start, until Windows is booted for the first time, _or_ unless the user manually chooses "repair the install". And this is with Microsoft's own msi installer system, mind.
Linux makes life easy for the application developer. Real easy. Most of us app developers don't realize how easy we have it until we try to port to Windows (or OSX).