I also don't believe it's about memorizing word for word but the way most of these incremental reading apps are designed rely on cloze deletions to create the "

I also don't believe it's about memorizing word for word but the way most of these incremental reading apps are designed rely on cloze deletions to create the "flashcards" and so it is in a sense training your ability to recall word for word. I can see incremental reading being good for researchers who might benefit from widely and incrementally reading an enormous number of papers over time. But in general, I think you get more improvements in knowledge and skills by going deep into one resource as opposed to going broad. Not to say you can't do both though. Spaced repetition seemingly falls into the same problem, it's easy to fall in the trap of making more and more cards without questioning whether or not you'd be better off doing other tasks to solidify your learnings.