So it is the level of "privilege" that does or does not allow the commission of -isms then.

No. It is the presence of privelege at all in the first place that holds all of us responsible to address that privelage as a reality when protecting one another.

The better off the target is, the more acceptable discrimination is?

No, I reject that characterization of what intersectionalist feminism is altogether. Read further for more.

That is also a very Western perspective. It would be ok to tell Muslims in the Middle East that terrorism is their responsibility because their country's power structure does put Islam firmly above others?

No, because you are equivocating two different meanings of “responsibility.” Feminism calls for a brother’s keeper responsibility, not direct culpability responsibility. It is absolutely valid for example, to expect Islamic leaders or followers to speak out against violence — and they absolutely do without you or I even asking. Much similarly, I ask Christians in the U.S. to recognize their position of power and to speak out against christofascist or transphobic violence, and that happens also (though perhaps less frequently than I would like). On the same level, I ask all men to take brother’s keeper responsibility and to hold one another accountable, recognizing their position of privilege while taking steps to protect others, especially when it comes to listening to women expressing their lived experiences rather than talking over them.

It’s a subtle difference but so incredibly important, so read it again if needed. Brothers keeper responsibility, not direct culpability.