It's interesting to read that you slowly shift the narrative from accepting your faults to making excuses to blame externalities, like inherited narcissism and ADHD. Look the word up, it's essentially an umbrella term that pretty much describes anything that can be considered negative, almost to the point that it's meaningless, except as a convenient tool to antagonize people. Selfishness and self-admiration is spectrum, everyone possess it one way or another. To claim otherwise is inhuman. Clearly, there are actual extreme narcissists, but they are not as frequent as people use the term loosely nowadays. Disclaimer: not a psychologist, but probably neither are you.
I don't think he was trying to justify or excuse his way out of his bad qualities in the second part; It felt more like he was pinpointing the reason. I'd say it's okay for people to give reasons for bad actions as long as they they still admit to wrongdoing and don't use that reason as an excuse for it being okay.
There are companies like Evernote/Zight/CloudApp that at one point tried some things like this, but they never really caught - I think because it's pretty easy to add annotations yourself or some note of your own - and a screenshot not "trying to do everything" is part of what makes them useful & ubiquitous.
The apps don't have to know a screenshot was taken for this feature to exist; they could write into a passive "in case a screenshot is taken, use this as metadata" object data field that the OS uses when the user takes a screenshot