I have to begrudgingly agree with the guy with the guy in the article, as someone who has both consoles and has taken them both online the PSN community is a bit better. I will explain why.
At first I was tempted to fire back with the obvious ammo pointing out another article here on "The Escapist" about a PS-3 user complaining about "sexual assault" online. Both idiotic for the person who did this, and the person making the complaint. I'm surprised nobody else bothered to mention this in scanning two pages before I responded.
On the other hand, I have played in both communities, albeit my friends lists are nearly empty since I'm really a "single player" kind of guy unless I'm in a full fledged MMORPG where I am exactly the opposite.
Going by my online "passion" for fighting games, even though I'm not very good at them competitively, I noticed a lot more immature behavior on XBL than on PSN. Not just in terms of what people say, but in terms of people doing things like disconnecting when they are losing, or filing "poor sportsmanship" complaints against people who beat them so they won't have to face that player again and risk losing more on their ranking.
While I do not use Home (currently, though I have a chatpad on order and plan to try it eventually) I also think it is responsible for a greater degree of maturity despite what you might hear. XBL really doesn't have any kind of general access lobby or chat to meet people, rather it's "social components" are based almost entirely around the idea of inviting people you already know IRL, or maybe running into someone in random games. When it comes to the latter it seems there isn't much in the way of conversation or interaction other than trash talk, where on PSN people do randomly meet and shoot the breeze despite everything else.
There is also the issue of XBL being a pay service, people who pay for access to online multiplayer are "harder" to police because Microsoft doesn't want to lose their revenues. Rather Microsoft would rather focus on their build in "Ignore/Avoid" system than actually ban players like PSN seems to do more frequently. I'm looking back to the increasingly insane shut in who sued Sony (to begin with I had sympathy, but he jumped off the deep end). Even the potential of policing limits things substantially.
Having played games like "Demon's Souls" with limited player activity, most of my "phantom" experiences have been largely positive. I actually think the online experience would be VERY differant if the game was on XBL.
As far as titles like "Left 4 Dead" go, that's a fairly deritive shooter and I think it sort of relies on a lack of teamwork to remain challenging. What's more going from the very beginning of it's launch there have been endless stories about "the idiot(s) I ran into", not to mention videos and everything else. You see this with PS-3 games, but less frequently.
Oh, and I suspect the PS-3 pricing had something to do with it as well. A parent looking at both systems probably went Xbox360 because it was substantially cheaper for quite a while and the performance issues were minimal. This lead to more kids (the types without their own money) being involved, where the PS-3 crowd were more people with their own cash, even if many of them had been saving up due to being PS-2 fanboys. This means an older crowd at least to begin with (and of course there were doubtlessly exceptions). With price drops I sort of suspect things might change.
I also suspect Sony has shot itself in the foot maturity wise due to the lack of PS-2 backwards compadibility. People grow up fairly quickly, and it's been many years since the PS-2 was introduced. Those with enough games for the PS-2 to want backwards compadibility are probably not kids at this point (young adults at the oldest). With that feature removed from newer models (which has been a big deal for some), I think it's discouraging an older crowd of gamers, many of whom have these piles of games which are increasingly worthless even as trade ins, which they still want to play. As ironic as it sounds I personally know a lot of people who used the PS-3 as a PS-2 with the occasional next-gen title.. only to have thier system die and then head out and get PS-2 instead of replacing their system.