No it isn't. As many people have pointed out you can get clear unambiguous english spoken in a variety of scottish, or west indian or southern english
*accents*. To name but a few.E.g. a glottal stop is not an 'accent'. Its 'pidgin english' words elided and compressed to be almost undecipherable, but fine in the context of people who only know a vocabulary of maybe a 1000 words anyway. Their utterances can't be confused with the other 199,000 words in the English language because they think it is unreasonable for anyone to actually use them.
If not downright elitist.
"Why should we not be taught in Zulu in the township schools? English and Afrikaans is colonialist and elitist." "Whats the Zulu word for 'Philips head screwdriver' "We don't have one" "Is that a reasonable answer?"