RMT

[LilimoLimomo]

Ridding this game of RMT spam is incredibly easy.

With respect, if it were actually this easy, CBU3 would have done this by now. As you yourself imply, the solution you have proposed is straightforward and simple, which means that it's incredibly unlikely that in the span of a decade, an entire team of professional programmers wouldn't have considered this solution.

Thus, it's incredibly unlikely that the question to ask is: "Why haven't they figured out and implemented this perfect solution yet?"

It's far more likely that the better question to ask is: "What am I failing to consider that made them not move forward with this solution?"