Yes, and your points don't contradict mine at all CGI.
Topics can spur discussion towards other topics AND people can be so locked into their insular, group supported opinions that they can't see there's a much wider perspective of opinion outside their group.
If anything - the fact of the matter - that a bunch of PS guys got caught up in a discussion of current Gen PS exclusives, when attempting to engage in a discussion about either platforms' strengths and wider appeal in the next Gen - seems to support your observation (that conversations can drift from one topic to another) AND my observation (that some "group" opinions are so insular and disconnected from the wider cross-group opinion, that they can end up having an internal discussion when trying to engage with larger/other groups). And both our observations could easily be pointed at no particular party beyond "all of us video game forum posting types" - regardless of platform affections or affiliations.
