Sure, but there aren't that many useful spells in BG 3. A level 12 Sorcerer could just get it from the Sorcerer spell list and have more metamagic points. Not saying the flexibility isn't useful - it is for sure, but the overlap between Wizard and Sorcerers spell is so huge. You probably want to also get something like Sculpt Spells out of it, for it to be really useful.
Wizard 1/Cleric 11 is more of an issue.
Oh don't even tell me that a Wiz 1/ Cleric 11 can learn Wizard spells up to the cleric level of spell slots they have...*facepalm* - I agree, that is actually MUCH worse.*
Yeah, that's "working as intended" - sheesh.
It's honestly beyond indefensible at this point and anyone doing so is arguing in severely bad faith/trolling.
*Although just want to point out there ARE wizard spells in game that are NOT on the sorcerer spell list - which is correct according to 5e. Like Create Undead, Flesh to Stone, Otiluke Freezing Orb, Otto's Irresistible Dance, Wall of Ice, Planar Binding, Conjure Elemental and many more. So this exploit gets you access to those.