"It seems like the majority of the comments opposing web apps oppose them because they're cross-platform and not written specifically for their chosen platform, which is a very silly stance to have."
But it's not. By not being written specifically for the platform, everyone is just getting a least common denominator approach. Nobody is getting anything that integrates with their platform. Nobody is getting anything that embraces what makes the platform special, or good.
"but a lot of the rhetoric around here really reeks of elitism."
No, it's more that we want developers to actually make an effort to embrace the platform they're trying to work on. And, quite frankly, use something that's not JavaScript. Learn a second language.