i tend to trust Nielsen on this one, who literally wrote the book on quantum computing and has spent years teaching it to people. his philosophy is that the biggest obstacle to understanding is memorization of basic concepts and notation.

You're right that the spaced repetition questions are different from the really interesting questions, but that's the point. They're supposed to be aids in internalising the "lower-level"/"boring" terms, definitions, properties, etc., which is necessary to be able to follow along.

Of course they are. By design the flash cards are small atomic pieces of knowledge that can be answered simply. If the grand overarching concept is a web of interconnecting ideas, then the flashcards are supposed to help you maintain that by making sure you don't forget the small ideas the structure is made of.

It's also by design that some of the questions are, as you say, laughably simple. It's to catch people who aren't properly engaging with the text as early as possible.

Nielsen and Matuschak are sensible to these sorts of critiques. Quantum country is part experiment after all and they've been learning, adjusting, and experimenting with what works best. If you want a bit of context of where they've come from and where they want to go, I recommend this: https://numinous.productions/ttft/