That is simply false. Botting happens in every single game that requires upfront cost. This game in particular allows them to farm income directly instead of "selling in-game assets for gold to sell to players in a 3rd party market." This argument make no sense at all. The return on investment is worth the upfront cost.

Edit: One example is WoW. Its plagued with bots while requiring to buy the game full retail plus paying a sub fee every month. Thousands do so gladly and are profitable.