If you are going to leave out Novgorod and Florence for not being Merchant enough, including Gotland is rather confusing...I mean, when you compare Gotland and Novgorod (or even the Swiss!) for historical importance, there is no comparison at all, and wasn't Gotland mainly a republic of farmers anyway? And hardly even a proper "republic", let alone a merchant one. It hardly fits the definition of a "Merchant Republic" better than half a dozen others. The restrictions seem confusing and inconsistent. I really hope I don't see some fictional "Gotland Republic" dominating trade in the Baltic in most of my games, it would be completely unrealistic. It should be a trade post of the Hanseatic League at most.
There is sense in what he says.