Was it fair?
For all practical purposes, Meryl was a world class professional dancer (in a different style, but still) before she ever got to the show, very accustomed to working extremely hard, is in the kind of physical condition to be expected of an Olympic and world class athlete, is super-flexible, and is absolutely gorgeous - the latter has to be a major factor in the audience vote.
She was so good, that it sometimes seemed like her DWTS partner was the limiting factor, though perhaps I mis-understand.
She was competing against fairly normal people, some of whom had little or no dance experience. How much chance did they have? It would have been like pitting those normal people against the winners of "So You Think You Can Dance", for which they seek out professional and semi-professional dancers. That's not fair. Would you pit ISU Worlds skaters against LTS skaters?
Meryl WAS almost beat by the sympathy vote for a disabled person who had lost her feet - who did really well, all things considered, but that person had to be carried off the set, and could not move her "feet" up to the standards of serious dance, always an important factor in judging land dance.
One very minor question. Aren't the "Dance flicks", where the dancers alternately quickly flex their legs behind each other, one of the defining moves of Cha Cha, without which any Cha Cha performance is considered lacking? Unless I missed it, Meryl didn't do that move. Should she have?
As for Charlie ... See a performance that helped eliminate him:
Notice the judge criticisms. Also note that he doesn't have the right facial expressions to match his DWTS partner, and isn't always graceful.
He was considered by many to be as good as Meryl in their ice dance partnership, in part because he is remarkably strong, has great posture, and skates with tremendous power and speed - not all of which is useful in some of the dance styles on DWTS, like in that video. IMHO she was always the one who had the great facial expressions, the flirtatiousness, and the great acting ability.
On top of that, it has always been unfair to judge male and female dancers the same way, when their dance roles are so different, especially in a reality show where the audience vote is so important. They don't make that mistake any more in "So You Think You Can Dance". They shouldn't make it in "Dancing With The Stars".