Saw someone fighting to defend a famous ptero design with bird wings instead of pterosaur wings by trying to reason they wouldn't be able to play the guitar.

First of, nobody would even mind the angel back wings if it was pterosaur wings. Second, even with pterosaur wing hands it's pretty feasible, as pterosaurs had plenty of flexible wing webbing so that an anthro character could easily play a guitar.
"The animal with fingers can't play the guitar" is not a strong defense for a design choice that's bizarre, at best.