I'm sorry but this imo is wrong, to say that different platforms don't attract different demographics is incorrect, the question though is how blurred the lines are between them, and also like I and another chap has already mentioned there is no way considering the high price at which the PS3 was previously that it attracted the same demographic as the 360, and that foundation is still there, although like I said that will change now due to the price drop, I personally see the PS3 as a more 'mature' console, it's interface, styling, and previous pricing has most probably attributed to that (although I know in actuality it may not be the case, I'm talking about public perception here), you only have to boot up the 360 for the first time with it's cute avatars waiting to greet you to know that MS are aiming their console at a more 'casual' audience these days, Natal will back that up later this year, my mum for example purchased both my brothers 360 last Christmas because "all the kids at school play them on-line and use live to chat to their friends", now that's a good thing tbh, it shows how successful Live is, but at the same it shows the type of demographic it's pulling in over it's competitors.
End of the days all systems are going to have thier fair share of ass-hats, and there are different factors including number of people using head-sets/mics, type of game being played etc that attribute to peoples awareness of these type of players, but at the same time I do beleive that there is a disparity between the types of gamers on each of the platforms.