Yea this article sounds like a good strategy on how to get correct answers on a test of things you don't understand.
I just think the categorization of "textbook" is nonsense to start with. Of course you want a book with text as opposed to a picture book.
You have to start with the right book. The variability between books on a subject is so huge and probably even different person to person based on prior knowledge.
Memorizing and learning are the same process to me. What would be different is attempt at retention.
However, this is not strictly necessary because when you relearn a subject, you often relearn it faster due to previous experience(memory) with the subject matter.
If your goal is to retain skill/knowledge over time, than that's a different matter.
I'd agree if we were living in the 1800's, but we're not. We're living in the age where everything is googleable (Including the text book). You don't have to memorize things to have information.
Even in the 1800's, in a good library, I'd have more information available in a searchable, indexed form than I could quickly read into "working memory" to be able to "process" with.
Having a Grey's anatomy book in front of me, all available to read, does not make me able to perform anatomy at an advanced level.
It's similar to having data in secondary storage, that still needs to be loaded into a process's working memory, before it can be worked on. This is specifically true of condensed terminology that's used to compress further explanations.
Following the anatomy example - if I don't have the terminology to describe the different positional views available without doing an external lookup first, following a basic description becomes very difficult and involves so many lookups as to become impossible to follow.
I can't find the article/paper, but I remember reading something where someone calculated the trade-off for a specific API between knowing a percentage of the API method signatures of by heart versus looking up each one using the IDE documentation each time. It made a very big performance difference in the end.
BTW: knowing what you don't NEED to remember and can just reference when required, is probably part of the skills making you an expert.
if I want to learn something I want to understand it, so that in the end I'm having a high signal to noise ratio but if I memorize things I don't necessarily understand them leading to a low signal to noise ratio
The advantage to memorizing a textbook is you can learn without it. So if you can memorize quickly but learn much more slowly you can use time that's otherwise lost (like the two hours of mandatory daily driving in the US) for learning.
Memorizing a text book has very little to do with learning a text book.