You seem to have the idea of PLing a bit mixed up, I'm guessing from XI. Power Leveling in most games is where someone gets the exp for you by either having you in the party while they destroy high level monsters and you sponge up the exp, or getting on your account and doing it all for you (the latter being what RMT are offering). What you're talking about is something completely legit, and just helping people out. You'll be fine, no one in their right minds would ban someone for following a friend or stranger around and healing/raising/buffing them.