Now, that my account got finally unblocked, I’d be happy to correct the inaccuracies here.
First, my prediction (not “supposition”) is motivated by the contents of the overwhelming majority of self-help pages returned by a simple Google search on the topic. I included a sample link in my first post above. And,while I did repeat my prediction a few times, I always decorated with “predictably”, i.e. did not present it “as a fact”.
Second, I’m not at all “content to risk mucking up your system python”; BUT, I do have a few simple rules of hygiene that completely eliminate that risk, which makes me a collateral victim of this PEP. That’s also what “gets under my skin”, as @fungi so aptly put it. BUT, I can see the value in stopping people without such self-imposed rules from shooting themselves in the foot; especially from the perspective of increased support burden. I just wish that this had been done without forcing the same remedy down the throat of those who don’t actually need it… (see more on that in my next post below)
I can also sympathize with the idea that a big scary flag is likely to make some people think twice before they copy and paste the solution from StackOverflow or some other trendy page. I’d still predict a good 50% rate (or higher) of people who will simply turn off the intended protection, but I obviously cannot know, and on that point you are exactly correct. Time will tell how effectively this PEP works its magic.