It has everything to do with it. The reason FFXI and early Wow players didn't behave like Halo & Call of Duty players was specifically because the people they partied with today we're very much likely to be in their party the next day. Performing well and being a general joy to be around might be the difference between being invited to a group the moment you login the next day, and having to sit with your flag up for an hour - or longer. I knew a few characters that couldn't get into a raiding guild, or even a pug group for the entire duration of WotLK because of their in game behavior. I also know a guy that was blacklisted personally, and he had alts that he didn't dare step out of line on for fear they'd get blacklisted like his former main. He didn't find it as funny as I did that he had to make another rogue to raid on.