This. At first on the early mailing lists I participated under my RL name, but with the shift to blogs and then LJ I switched to using a pseud because I did not want search engines for my RL name to give as first result the fandom stuff, since then I was still at university and had no idea whether I wanted to pursue a professional path where you might not want the first google results be your thoughts on porn. Also, associations between pseud and RL names aren't necessarily bi-directional, i.e. I never minded fans knowing my RL name, it's the reverse lookup I've always been more wary of.