While game design is going to strive to provide the optimal user experience, game design in and of itself is not the solution to player conflict. Aside from varying skill levels (which game design can compensate for to some degree), there will always be a range of emotional maturities, players that have varying social backgrounds, moral codes, etc. That is why every game has a TOS. I would dispute that in FFXIV there is a "non-trivial" chance of encountering TOS violations, however if your definition of "non-trivial" is zero there I would agree with you. However, I would also say that zero is a non-realistic expectation. Whether violations are followed up appropriately - that's a whole other discussion.