To that makes perfect sense. You get charged for usage of their service and they chose to do that by assuming an average usage per license / person and charging that. When you get to cram in more usage/person by using a third party, they either charge you for access via that third-party or that could also just increase prices per personal license. I guess they figured the latter would be less popular or they can't do it, because they have existing contracts.

They don't care about your headcount, but you do use more service.

Totally makes sense IMHO. Even subscriptions are essentially a simplified/averaged "pay for what you use".

The question is rather whether a single type of subscription license makes sense (e.g. when AI burns through more resources than the average human, should the subscription go up for everybody? - as a human I would be pissed to subsidise heavy AI usage by other users).

E.g. there should probably be special 'AI licenses' similar to how some products have special 'CI licenses'.