Vladimir_M and Nominull have got it right.

Vladimir_M:

You say, "pretending to be offended for personal gain is... less common in reality than it is in people's imaginations." That is indeed true, but only because people have the ability to whip themselves into a very sincere feeling of offense given the incentive to do so. Although sincere, these feelings will usually subside if they realize that nothing's to be gained.

Nominull:

Here I am going to repeat again that I do not think that Muslims, game-pacifists, or feminists are consciously conspiring. I think, rather, that it is natural to take offense not only at things which are actual norm-violations, but also things which you wish were norm violations, things which would boost your status if they were norm violations. There is no conscious consideration of this, but somewhere deep in our hypocrite brains, we decide to pretend that our desired norms are the actual norms.

Although one function of offense is to alert about real threats, another function is to grab any status that it can (except when being thick-skinned grants more status).

Offense can scale depending on how much can be gained by it.

Btw, I first heard this concept from PUAs claiming that a girlfriend will "dial up" or "dial down" the drama that she gives (without any conscious goal-directedness) depending on how the man responds. This tendency seems to be a general principle of human psychology, not just female sexual psychology.