The reason why was obvious. The local business operators, who were mostly older white people, didn't want to buy from a Chinese person.
Asian guys I knew were resentful. Not only was it racist to do that, but the whole situation was racist. It was a racist response to a racist situation, and it made racism seem hopeless.
As far as accents went, we didn't have them, by and large, unless one was an immigrant. The most common accent was a Chicano English accent.
There's a logical inconsistency between saying a) Don't judge people on their accents, listen to the message and b) Fix your accent.
To pg's credit I think he frames this purely on efficacy of communication ( it's similar to typing out better phrased emails) but that ignores the other reasons people with accents get judged.