We live in a time where we don’t actually need a good memory anymore. When we want to know something, Google does the work for us. Most of the quests for certain information are done on the Internet these days. You’ll find an answer to about everything you ask for.
In magic, you’ll find almost everything you want to know by simply typing some letters and hitting the return button. Google will present you with sometimes hundreds bits of information. But is that any good?
I doubt it. Of course, you get access to the information. But there is a difference in quality in comparison to the “active” knowledge you acquired by reading a book, or practicing something. This knowledge is deeper, and it is real knowledge, not just some information you fetched and have forgotten a moment later. It is knowledge you can use, and that is available to you all the time, and without the Internet. It is “quality knowledge” ready to be used for a prupose.
This is the kind of knowledge you need to perform “deep work”.