The fast travel system helps out small tribes far more than it would ever hinder a mega tribe. a small tribe will generally be close to any territory they have claimed, as such they should be able to defend easier. a mega may have people on the other side of the map that they are trying to coordinate with. there shouldn't be any ranking in this game to be honest. at least not just based off of how much land you have. there never should have been any "prize" or "reward" for such either. that was a stupid mechanic to put in. limiting the amount of territory a company can have would increase the trade factor, the reason for companies to work together, etc. removing fast travel would do none of this. all that would do is force the people to be tied down to a specific area and go nowhere else for fear of losing that territory.