It’s obvious owners will pump their game ratings and (maybe) “jealous” non owners will be overly critical. But we have to assume that this is the same for all reviewed games.
So the rankings will still be an accurate aggregation of opinions showing where a game sits relative to other games.
If you follow some of the Podcast elimination bracket segments (eg H2H), the game ranking always end up being the same as the Pinside rankings. And that’s just 2 guys with little bias debating the merits of each game vs another game. Or when they do it as an online poll, it also matches the Pinside rankings.
Individual comments on the other hand are by definition purely subjective.