I'm guessing what abatt is saying is that Guillem et al did not become famous because they were "self-promoting publicity machines" but rather because of their excellence as dancers. Even your own description suggests this:
"in London during the 1990s where it seemed Sylvie Guillem, Darcey Bussell and/or Viviana Durante were plastered on every street corner in the city between public transport, magazine covers, newsstands, posters, etc"
That doesn't sound like mere self-promotion, it sounds like fame.
I think it's both. I think all of those dancers are famous because of their dancing, and I think they've also sought it out, Bussell especially. There are plenty of famous people, even strikingly beautiful ones, who do not grace major magazine covers like Darcey Bussell. (Actually, Bussell's self-promotion machine is very similar to Copelands with magazine spreads, books, and reality show judging, so I think it's very apt comparison).
The point I was trying to make is that if you don't mind the publicity machines that those dancers (and as I said, especially Darcey Bussell) are, then what must irk you is the origin of Misty Copeland's fame, what makes her noteworthy. I do not disagree at all that she is not the dancer that Guillem, Bussell and Durante are. Her accomplishment is because of what she has been able to accomplish being who she is.
Now, you may not think that it's noteworthy that she is the only African-American dancer of her stature and seniority at a major company, but a lot of people do. Or it may be that you don't think that that's enough of an accomplishment to achieve the level of fame that she has. I'm just trying to puzzle out what it is that bothers people so that she gets compared to Kim Kardashian.
I'll give you another example: Elvis Presley. Presley didn't really accomplish anything noteworthy musically on his own. He didn't write any original music. His music and stylings were derived from music that had been performed by African-American performers for quite some time before he broke on the scene. If you were to take who he was out of the equation (white), he was a fine performer but not someone who rises to the musical importance of many pioneers like say a Chuck Berry. So if you ask popular musicians who were your influences, he doesn't get brought up in the same way that someone like Berry, Hendrix, Lennon & McCartney, Phil Spector or Brian Wilson do.
But is Elvis Presley noteworthy? Of course he is! It's because of who he was, when he was and the music that he brought to white audiences.
I'm not trying to say that Copeland is Elvis. But there are a number of female ballet superstars. If you look at my earlier example, the Royal Ballet alone had Giullem, Bussell and Durante during the 1990s. There's still only one African-American female dancer at her level in the ballet world. Personally, I think that does make her exceptional in some way.