There is no unfair advantage, you're either a donor or non donor. I'm a non donor (minimal donor) and I understand that top ranks don't belong to me. Top ranks belong to donors. I'm a free player that's been in top 50 ships for a long time, also top 200 in arena since the beginning.
My point is, nothing is unfair. Donate to get further ahead or take a step back. Any game that has ranks and donors is this same way. Any person that says otherwise has not played paying ranking games. Put a non donor in rank 1 and donors will be upset (I've seen this first hand in dozens of Mafia ranking games).
Another thing to point out is peeps need to slow their roll on wanting content. You put too much in too fast and now the game turns into a job. Games are no longer fun at that point. I've been playing ranking games since these phones first started with them about 10 years ago. Making the donor upset and putting too much stuff in a game too fast will start the down fall to any game. (Sorry for typos)