If the villain character was able to instantly see and recreate even the most complex magic with seemingly no cost or drawback, how is it that they were never able to accomplish anything at all?
I don't think they put any thought into this, as usual.
I can only assume it's because in the og timeline, he was a lazy bum who didn't actually try to learn magic, thus over-relying on his memory without putting in the work necessary to develop proper understanding.
Photographic memory would be great for, well, memorization, obviously. Same with other grammar level information. However, as soon as you reach logic or especially rhetoric level knowledge, it stops being as helpful, since those things require you to think deeply about and properly understand the subject at hand.
TLDR: You can't learn something (very well) if you don't actually give a shit about it. And in the og timeline, the guy seemed to be a very typical bad-guy-villain-man type of character.
Oh yeah, also, there was also swordsmanship, which can't be learned solely by memorization.