I have moved on a long way from the days that 12 factor was my bible, but those days completely redefined my way of developing software. I'm not exaggerating here - it completely shifted my approach.
I guess it's similar to Scrum in that way - it isn't a great end point, but if you're stuck in the old ways (i.e. the methods used before it was even a thing) then it's at least a good approach to sink your teeth into, try it out, shape your approach, and move on from there.
Basically, I'd rather see a replacement that improves on 12 factor than throwing out the book entirely.
In 2023, yes. A lot of the 12 factor methodologies became table stakes in the modern cloud era. Back when this was written "cloud" was not nearly as ubiquitous as it is now, although we were certainly headed in that direction. A lot of the comments here are viewing this through a 2023 lens and forgetting it was written in 2011.