The trick isn't memorizing them. The trick is discovering them. I've been emitting various versions of Wingardium Leviosa at Spring Boot for days now, with no effect. Once I've learned the incantation I'll have it and can repeat it in ten seconds, but until I have it I'm producing no actual work.

Arguably, I'm more valuable because I have the capacity to eventually figure this out, rather than having already memorized it. But if this were a crisis rather than a minor bug, it would be much, much better to have somebody who'd already spent that decade learning all of the many, many, many incantations that Spring Boot requires.

(I'd also argue that Spring Boot in particular is much, much, much too dependent on incantations, and the main lessons I've learned could be put on my resume as "Expert in Spring, and you can be too in one lesson: Don't.")

That really applies to all ecosystems. Hiring somebody smart is better. But there really is something to be said for having somebody with X years experience, who can therefore do some things in 10 minutes because they've already done the painful part on somebody else's dime.