You might be well-served to differentiate between "Enterprise .NET" and ".NET". I'd agree with a lot of what you're saying if it's applied to folks who "think in ASP.NET", but outside of that? Not so much. You've got Mono developers, who tend to bounce between Windows and OS X pretty regularly and a bunch of other folks who are at least aware of the stuff on the other side of the fence. And then you've got folks who use it as a tool--appropriate in some situations, not appropriate in others.

(As noted in a sibling comment, it's also very common to see people turn their brains off rather than entertain .NET as a sometimes-appropriate tool.)