"...the world is full of delightful cultural corners each of which has its own eddies and currents of how to communicate well. To navigate the world, then, requires a certain willingness to pay attention and receive the picture sent to you as it was meant, not as you think it should be."

Sure Amos... and if I visit someone in their personal surroundings, I make every effort to grasp nuances and absorb their flavors of language; but when I go to the grocery store, it bothers me to find employees who cannot answer a simple question in coherent, comprehensible ways.
(Trying to use a self-checkout lane last year and the machine had defeated me..up comes a 'helper' who said "Na flrty bam goozen...je glom dizen"...."Huh?", says I... "Delem sturegie verusl" says she, and pushes all the right buttons. She knew what to do, but I have no idea what she said. ANYONE in that position needs to be able to handle basic English)

Best example of my concern:
Ebonics in Chicago schools

I heard a black educator on the radio once defending Ebonics. SHE spoke well and could switch back & forth, but was NOT, as far as I could tell, suggesting that kids needed to emulate her.