People are still making the mistake of thinking that fargo rate is skill level. It's not, it's performance. Any number of things can affect performance. Someone could be a 600 fargo but skill wise be a 750. They tweak one thing or start practicing more and bang, they're winning tournaments. The reason you don't see it that often is that players aren't often increasing their practice or discovering the thing holding them back in competition. That's not even taking into consideration that the way fargo tournaments are structured, the players in the 600-700 range will be kept artificially low if they are only or mainly competing against lower skilled players for the reasons I've already mentioned.
If they were to exclusively play in higher level open tournaments, their fargo rates would be higher.