Memorization is sometimes mistaken with the absence of richer learning, but I think they can coexist (and fix that “brittle” feeling). I would say that learning most things involves at some point or another remembering information “like the back of your hand”, i.e. you do not remember how or why you learned this fact, but it became ingrained in your memory. Remembering that piece of information alone is often useless without the greater context (e.g. how to take the derivative of an exponential function without knowing what a derivative is), but still seems to be a part of the learning that is happening. The worry here is that memorization would “remove” the connection from the more “connected” learning happening, but I’m not sure it needs to.