Do you want an echo chamber!? Ever played a game that got 95+ and thought what were they thinking? You are gonna continue to get this if you JUST allow fans to do reviews.
Secondly everyone at some point wasn't a fan of souls at some point an then they played it and they were. These group of people are growing with every release so they should probably be catered too.
Maybe people that hate a genre shouldn't review a game but newcomers, people that were lukewarm in the past and people that haven't tried the series in a while absolutely should. The criticism will be more varied and better as a result
Considering Souls games have been going for 13 years, it's probably quite hard to find members of staff who
don't have experience with Souls games, whether they loved or hated them. Unless you're just starting out, frankly it would be pretty embarrassing to be someone paid to play video games and to have NOT experienced one or more by now considering the industry impact they've had.
Frankly I don't want someone that's inexperienced with a genre/subgenre telling me about a game, I want an """expert""" opinion, the word being used very loosely. I don't play JRPGs much but I want the big JRPG fans to recommend to me what they consider the best JRPGs, not someone who played literally one and thought it was great. I can do that myself. If longtime Souls players band together and say "this is the best one yet" then that information is absolutely valuable to someone who's not played any.