"Truth is, most of the things I know about the world in general and programming in particular is due to procrastination and rabbit-holing". Excepting hobby areas (where it doesn't matter) I think you're kidding yourself as without a disciplined framework for learning any knowledge you acquire is at best accidental, there will be too many gaps for you to even comprehend what you don't know.
Tests and exams are there to ensure you have done the hard non-fun-stuff as well as the fun-stuff and to "prove" you have understood, not just regurgitating half-comprehended factoids. You are advocating the equivalent of a educational junk food diet, the only thing you'll absorb is the superficially interesting and the crap.
Serendipity has its place but if it is your principal approach then you are delusional.
I'd suggest that not following rabbit holes can lead to a shallow understanding. If you descend into a rabbit hole, it's because you realized there was a gap in your comprehension and decided to look into the matter and fill in that gap. If you successfully resolve the issue and then return to solve the original issue, your end result is a complete working demonstration of your improved end-to-end understanding.
Tests and exams are there to ensure you have done the hard non-fun-stuff as well as the fun-stuff and to "prove" you have understood, not just regurgitating half-comprehended factoids. You are advocating the equivalent of a educational junk food diet, the only thing you'll absorb is the superficially interesting and the crap.
Serendipity has its place but if it is your principal approach then you are delusional.