I disagree with that and see it as an over-hyping of premium. By no means is premium the key to the game; it only gives a small advantage at best. And your argument about the mines is pretty invalid, considering that the mines create barely 10% of my total resource production.This is amusing. I think it is obvious that if you want to be a top player you must use Premium features. Like crack2live was saying, the reason premium exists is to give players who have it an advantage. The advantage will not compensate one on being stupid. If you don't know what you are doing and you use Premium then I doubt you will be heading the top of the leader board. However, between players that are extremely active, and know what they are doing, then premium is a definite advantage and I am beginning to see, as a necessity to be in the top 100. No doubt about it.
This game is very much like a microcosm of capitalism. If you have wealth it's easier to acquire more. By that I mean, if you have a high point city you probably have built up your mines and camps. Thus you can build up armies faster , acquire bp faster and conquer more cities faster. The slightest advantage in early game ripples through the course of event in the entire world.
I have heard the argument made by some that when you get into the top position it can become a spending game rather than a war game. I don't know how accurate this is since I have never been in the top position but I think it is a possibility.
The argument about activity is kinda absurd in my opinion. Unless someone gave their life entirely to grepolis, shunned sleep entirely, etc. they would have no chance of being in the top 100, lets say two weeks after the world started, if they did not use Premium. Even if you shunned sleep and stayed glued to the screen someone using Premium could easily pass you up.