I wonder if “calm computing” concepts have overlap as a principle, if it means less notifications is less things running in the background, and less complexity? Not exactly for the same purpose. Especially since I see calm computing more as not letting a machine hijack your attention or manipulate you.

It is a central idea in permacomputing to keep the user aware of what is going on in the system. But awareness is very different from attention. Even if there's a lot going on in the system, it's not an excuse for stealing the user's attention.