> it's just that I have never really found that memorization was ever an obstacle to my ability to learn something
I mean, taken to an extreme, that's clearly wrong - if you had no working memory (or, say, forgot everything after 10 minutes), you also couldn't learn anything, at least in the sense of being able to use that knowledge long-term. Learning and memorization go hand in hand - learning is, in a sense, the act of getting new things into your memory.
If you mean that there's more to learning than just memorization, you're right! (mostly, see note) In many domains, you need more than just to try and rote memorize a bunch of facts. E.g. when studying math, you need to memorize things like definitions, but also understand them, which is another way of saying "memorize what they really mean". You need to "memorize" how to solve problems. Etc.
You certainly need to have that initial understanding when reading the material the first time, otherwise you can't possibly remember it. But, all of these can reasonably be called memorization, because they are all things that you might know one day, but get lost over time, and are things you can "drill". Therefore spaced repetition is a good way to make sure the stuff you learned once will stay in your memory long term.
Note: some things are pure memorization of facts, in a sense. E.g. I memorized all the locations of countries of the world, then their capitals, and now I'm working on their populations. There is some understanding that goes in here (and one of the reasons I do it is because it forces me to learn more about countries and make interesting connections), but for the large part, this is just brute "practice this fact enough times" learning.