The joke response is that building your own PKMS is the final form of procrastination.
The frustration for me is that I use a PKMS all the time: Google Keep.
Cause what I want from a PKMS is a note book, maybe with a way to tag each note, but only if it's convenient. The cardinal sin of any PKMS is lack of access. I don't want my PKMS to show a loading screen when I open it. I don't want it to bury me in options about what type of note I want to create. I don't want my PKMS to be loaded with so many features that it takes a second or two to switch screens.
I want it to be easier than the effort it would take to carry a note pad and pencil in my back pocket, and it's astounding that it's rare and sad that I have to resort to Google's blessed tendency to abandon projects like Keep to bare minimum functionality for me to get the app that I want. Will I use Keep for 30 years? Idk, but I've been using it for a decade so far but knowing Google it's any day now that they'll just announce that they're canning the whole thing.