Probably my favorite part as well (and as you pointed out, easily made setting-agnostic). I feel like I'm having a brain fart though on Candlekeep perks (p34), Arcane Secrets. They have the recipes gated behind Arcana roll bonuses, which quite quickly climb to +12 and +15. Without optional rules (multiclassing or feats) isn't a +11 the best Arcana roll bonus a wizard can get? +5 INT and +6 proficiency? I know the library isn't exclusive to wizards, but it seems weird to have 60% of the list be off-limits to even the most powerful archmage.
(On a side note, I don't know how the Archmage in the MM has an Arcana skill of +13, but "monsters" don't have to follow character creation rules, so I figured they just gave it expertise because they wanted to.)
Let me know what I'm missing here!