My Android phone prevents me from recording phone calls at the request of my carrier, even though it's totally legal for me to do so in my jurisdiction.
I'm not loving where this is all going.
The most frustrating part about this "feature" is that you don't know it's enabled until the screenshot is taken and you're left with a picture of nothing.
That and some app authors thinking they're protecting you with this (referring to banking apps in particular)
Beyond preventing screenshots, it blacks out the window content in the task switcher, which is useful if someone is looking over your shoulder. This, by the way, is a good way to check if screenshots are allowed. If the window appears black in the task switcher, screenshots won't work.
The idea is similar to the "**" password fields.
Password fields are inputs. Screens are bi-directional.