I am fully in agreement with the conclusions drawn in the article, but the bad news is that even with those techniques it can be a slog. Any Anki user will tell you that maintaining dedication and avoiding burn-out is your Achilles' heel, not the limits of your human ability. Understanding something for the first time (in the Feynman technique sense of being able to explain it well), and doing that multiple times per day, takes up a lot of mental energy even if you are smart and naturally talented.
In conjunction with using memory techniques, we need to add dietary practices where we become much more selective with the information we take in. Places like HN give the illusion of learning (and to a great extent help broaden your mind about certain topics), but the actually utility of all that random knowledge butts up against the opportunity cost. There are already many more worthwhile pursuits than can be fit into your lifespan.