We see the same thing from various hapless "alt OS" communities (e.g. Amiga, BeOS) where most software is binary only and Free Software isn't generally expected. Someone finds a dozen GPL'd SDL games, they compile the source, tweak a few lines here and there to workaround problems, and then they just upload the binaries and say "Look at all these free games".
The idea that they're responsible for providing source code is completely alien to them and they're often very hostile to anyone who points this out. They see what they've done as taking a free resource (the source code) and making something useful from it, for which they should be praised. Despite the fact that they themselves relied upon source code to be able to do this, they often characterise it as "useless" or "confusing" in explaining why they should not have to distribute it.
When it comes to their changes (if any) again they tend to be hostile to providing these. Apparently my source code is worthless, but their ten lines of changes are precious and they don't see why they must share.
And the overall effect is exactly what the FSF would predict: Such platforms often find that software cannot be maintained because someone threw away the only working version of the source code. New users can't learn how to fix or improve software because they're presented only with "ready to go" binaries and no source code. This is great if you want (as it seems some of these communities do) to create a cult atmosphere where software developers are like gods, but it doesn't do much for your chances of long term success.