While intrigued by the concept, I can't help but wonder, what's the value in this type of exercise? Or maybe that's the wrong question; maybe I should be asking "how does one realize the value in this type of exercise?"
I've seen plenty of examples of digital gardens that are basically blogs trying to use a fancier name, but also a few that are genuine learning exercises. The former aren't really interesting, but the concept behind the latter -- doing one's thinking and learning out in the open -- definitely is. Learning is a messy process, and there are always mis-steps and failures along the way. For a knowledge worker, especially one who espouses expertise in a certain area, exposing these mistakes would certainly pose some reputational risk, right?
Update: This seems like it's worth remembering:
Try your best to be right, but don't worry when you're wrong. Repeatedly. If you feel uncomfortable, or like an impostor, good. You're pushing yourself. Don't assume you know everything, but try your best anyway, and let the internet correct you when you are inevitably wrong. Wear your noobyness on your sleeve.