For example, in the article the author laments that Buffett's wealth went up by $X, but he only paid $Y in taxes, and that's not fair to middle class people. But middle class people benefit in exactly the same way - if you pay $250k for a house and a year later because of a housing boom it is now worth $350k, you don't pay taxes on that $100,000 you "made".
If the whole world decides a random rock in your back yard is worth $10M, you shouldn't need to give the government $3M while the rock just sits there.