I don't know how hard the OP looked, but this is at least the third thread on this subject. For some reason, some people seem to have it in for Pixie. Why? What did she do wrong? We have even had people criticising her and Trent because they look like brother and sister, even though they are not really related at all.
Dance is an art form, which demands a degree of athleticism if it is to be done to a high standard. In common with any other art form, it also demands talent if it is to be done well. Talent is a curious thing, and something that I suspect a number of people on these forums simply do not understand. Put simply, it is an aptitude - an ability to do something better than most other people, coupled with the drive to achieve it. It is not purely founded on how hard a person tries. It cannot be taught. It is something that some people are born with and others are not. Training helps to develop it, but cannot replace it. That is why we cannot all be film stars or composers, or inventors or - dare I say it - dancers.
Pixie is talented. She isn't the only one. The same can be said of Frankie, Caroline and Jake. It is this, not whether or not they have had some dancing lessons in the past, that makes them stand out from the rest. They are also athletic in build, and physically fit, which gives them an obvious advantage over, say, Alison. There again, Mark and Judy are also fit, and Mark even has some talent - just not as much as Pixie. Is there something unfair about that?
One final thought. I wonder how many of Pixie's detractors are really put off her because she chooses to be known by her childhood nickname. For the benefit of those people, she is actually Victoria.