Quote Originally Posted by Curisu View Post
Exacly that.
And they have TOS gives reason to enforce that:

2.2 Real Money Trading, Farming and Power-Leveling. You may not sell, purchase or exchange for real-world money or value any in-game currency, accounts, characters, in-game services, or in-game virtual items. You may not play the Game for the purpose of acquiring virtual items or advancement in game play on behalf of a third-party or for the purpose of selling any virtual assets to a third party for real-world money, specifically including "gold-farming" and power-leveling services.
It can not be proven, but everyone knows that RMT is involved in one or another way.

2.8 Commercial Spamming/Spimming. You may not use (or abuse) the in-game chat and message services to distribute advertisements.
They falsly use the partyfinder function.

3.1 Sharing Account Information. You may not share your account or login information (such as your Square Enix ID and password) with anyone except your legal guardian, your minor child, or Square Enix. You are responsible for maintaining the confidentiality of your account and login information, even from your friends and family. If you violate this provision, you may unexpectedly lose access to your account to a third party without recourse against Square Enix. Square Enix will not be obliged to credit your Square Enix Account with Crysta or other points or awards, which may have been used by a third party as a result of the violation of this clause.
You only can clear certain advertised content by sharing your account data.
They might be able to use 2.8 but how is a PF entry going to prove the other two without doing either of the two points I brought up? Either people not breaking ToS in any way will get caught in the net or SE would need to get very invasive about out-of-game programs and what you're doing on your system.

Not sure if it was you or someone else who brought up the solo PotD runs, because that is a valid point and could probably strongly point to account sharing. But it's murky on other entries.