That sort of comment is more alluding to the possibility that since the member recently joined the board, it's quite probable they have simply joined up to troll and hate on the game in order to get a reaction and 9 times out of 10, that is the case.
Do they (the "trolls") admit to hating the game to get a reaction? A lot of members (especially younger ones or learning ESL people) have trouble getting their point across clearly, so they sound like they're trolling sometimes.
A lot of the time the people who point out the join dates have nothing else to say, except the occasional "/thread". If you've got solid refutations you shouldn't need to point out that the other guy's a troll anyway.
Well, if they admitted to hating the game in order to get a reaction they wouldn't be very good trolls now, would they? They're not always trolls, though. Sometimes it's just clueless kids bitching who shouldn't even be playing the game anyway...