Lets be honest, Farmhouses were implemented for players who cannot spend the bulk of online time used for gathering, but rather you can build a farmhouse so it will do the work for you, and it gathers at about a 3 person hand rate of each resource in its area. This is great! I love it!
All anyone should ever need is 1 per island. I don't care if you are a massive company, if that's the case then take your large player team and go harvest the old fashion way..
Limit players, 1 farmhouse, 1 market, 1 warehouse per island. per person/company All of which cannot be built outside a smaller area allowing others to place the same
The spacing between each building is also to large, make it smaller, thus allowing more people the ability to establish a foot hold and move onto other aspects of the game.