The key point (as noted in the upper right) is:
Understanding how something works can drastically reduce the need to memorize a bunch of seemingly arbitrary facts.
I believe this is an accurate statement. I've been around many people who seemed to be able to spout out the most arcane command syntax or provide the "textbook" definition of virtually any topic. But, if there was a problem where something more than knowing the definition of something or being able to quote the documentation on a topic was required, they quickly got lost and didn't know what to do or how to proceed.
Certification exams, for instance, ask questions that can be answered correctly if you've memorized a lot of facts. I've always jokingly said that if I gave my mother (sweet southern homemaker that she is) enough material to memorize, that she could likely pass the Oracle certification exams in 1 or 2 tries. And although she'd never indulge me to see if I could prove that theory, I suspect it's close to the truth. She's a bright woman with a great memory so I think she could memorize and do pretty well on the tests.
I once met a kid that had just graduated college and had started his first real job with a client I was doing some work for several years ago. The company paid for him to take a two week "boot camp" course and take the certification exams. So, with about 2 months of on-the-job experience, he went to the two week class, took all of the exams at the end of it, passed them all and returned back to work a "certified expert". Of course there was a big production flame-out right after he got back and he got razzed pretty good about "not knowing" what to do since he was now an "expert".
The bottom-line, as I see it, is that memorized knowledge can (and likely should) be part of your foundation. But, it will only get you so far. It's the ability to really understand something and how it works that will help you solve issues that just aren't solvable with memorized facts alone.