From personal experience, highly recommend this methodology. Note taking was always short-term helpful for me, but I found a step change in retention, etc.. by reliably reviewing new knowledge via spaced repetition. Another good article about notes as flashcards: https://andymatuschak.org/prompts/ (written by a collaborator of your linked article).
Also, agree re. Roam!
I've used flash cards in the past to memorize things for school - and I'd believe what he describes would really work for learning new complex topics by speeding up some of the basic memory stuff that makes you actually good.
I have a pretty negative impression of Roam though. They talk as if they've invented some new form of computing when they're another centralized document SaaS graph database that's a step up from notion/quip. I think there's real value there building a nice interface and they're probably better than existing options (features around links, etc.), but there's also a ton of bullshit from them that sets off alarms for me. They think they're xerox parc, but they're more like snapchat.