Harmful 
Nope. I'd hazard a guess that she can't even remember it because it meant so little - it was just part of a perfectly normal rounded childhood.
All this hysteria (and yes I am aware of the etymology of the word and it's connotations) - anyone would think you were all scared of your dd's liking it! Rest assured, it will be just one of a myriad of opportunities, and will mean literally zilch in a few year's time. You really won't be able to tell a child who has been so dreadfully brainwashed by a pamper party at six, to one who has never been to a pamper party in their life. Honestly.
And it is worth saying that I quite like these tales of bored girls getting fed up in the line. It's a grand way of reinforcing that make up is boring and not worth the effort
. It's very similar to how it works for dd1 with her dance - the whole farce that is stage make-up means that she never ever wears so much as a dab when she's not on stage...
A perfect way to illustrate gender performance. And at 6! Lucky lucky girls being invited to discover Judith butler so early! What an amazing opportunity for all the feminist mummies! And what a shame that none of them are embracing it, and are resorting to banning and secrecy. 
I'm pretty right on. I'm a paid up member of the Fawcett Society. Dd has been to a pamper party. I relish the opportunity to discuss this stuff with her. Stop hiding, people, honestly. You can't protect your children from the ills of society, you just have to talk them through it. It's far more beneficial and puts the kids in a much better place. For real.