FWIW, my Mum treated me like a doll for most of my childhood, pink, floral, dresses, matching ribbons, little white socks, ballet lessons- I was the definition of gender stereotyping- but far from being emotionally scarred by it, I LOVED it, and have a brilliant relationship with my mum. So absolutely no harm done, I had a lovely childhood and she enjoyed doing 'girly' things with me- win win!
There is no harm in encouraging typically girl/boy behaviour, the issue comes when parents ignore children's preferences and force them to be something they are not.
I highly doubt the child in question said to her mother 'Mummy I want a football party' and her mother turned around and said 'No, football parties are for boys, you are having a pamper party and I wont hear another word about it.' I assume that even if the suggestion came from the mother, the little girl was probably in agreement and is excited about her party!
Seriously, people need to lighten up! It's a bit of sparkle and glitter, not crack cocaine!