According to Wikipedia they aired music by Black musicians from day 1, with the Specials among others in their first program [0].
They were criticized for not having enough black acts. That's a reasonable criticism, but let's not make it sound like some kind of apartheid. They made a commercial decision about what genres to focused on, rather than something racially motivated. They didn't air many videos by country singers or classical violinists either.
Wikipedia’s article whitewashes the actual history. We were watching MTV and smoking weed in those Reagan’s America days.
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In fairness the US music industry had the race music chart which became the R&B chart to keep black musicians off the pop chart and Elvis’s controversy was singing black music…and consequently being played on white radio stations to white kids.
Lots of white artists were repackaging black recordings for segregated radio play in the 40s and 50s. It was routine in that era for any popular song to be covered by many artists within the same year, so it wasn't entirely insidious but there was a definite whitewashing going on with more than just Elvis. Georgia Gibbs is a notable case. Elvis' controversy was more the "sexualized" dancing which was among the things sanitized out of the covers.
They were criticized for not having enough black acts. That's a reasonable criticism, but let's not make it sound like some kind of apartheid. They made a commercial decision about what genres to focused on, rather than something racially motivated. They didn't air many videos by country singers or classical violinists either.
[0] https://en.m.wikipedia.org/wiki/MTV