> Help a tourist out, they'd do the same for you in their home.

Gracefully accepting corrections when your language is incorrect are part of receiving help.

If I were to write these posts in broken Itanglish do you really think native speakers would not correct me? Would it be acceptable to call them "narrow minded"?

I'm all for helping but please stop assuming that a US-centric point of view and language are the default for everything. For most people on the internet, neither assumptions hold.