Why can't I take screenshots off of any streaming service?

Question

Does that mean I get banned?

Update:

Like imminent or is it just gradual in particular. I am afraid all content gets blocked in an account. I mean I like to entertain myself with things, but how will I need to follow "das rules" of the subscription? Or I need to picture a device from another device and call it reference? Would that be alright to avoid circumventing at all costs?