I'd really like to know if a dip in wizard is intended to allow high level scrolls to be copied into your spellbook. I don't want to do it if it's a bug in the game, but if it's intended, I don't mind.
Yes thats how D&D5 defines it in the PHB, page 114, Wizard class, The Spellbook:
"Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a level for which you have spell slots and if you can spare the time to decipher and copy it. [...]"
All classes get their spoils. This is one of the Wizard. Wizards can learn maximum level spells in a multiclass; something no other class can.
Of course you still can only select a pittiful small number of spells from the Wizard if you really only take one level. But you can get the higher spells that you get through multiclassing.