I agree that it should be a great asset, and would be if the majority if the human race was understanding and willing to compromise. Unfortunately many people aren't , and quite often use religion as a reason for not being so.
To paraphrase, it is better to be ignorant of another's language and think them disparaging of us than to understand them and remove all doubt.
I was not aware that the 'blonde' thing was still a running joke. How passé.
Dialects would need an entire series of diagrams of their own. Just within England there's Cockney, Scouse, Black Country, West Country, Geordie, etc.I suppose there is no space left for dialects.