Just out of curiosity, is the reason you don’t think so that every other instrument requires two hands to play and therefore precludes the simultaneous use of a weapon? It's because material component means material thing, which a voice is not. Voices already fill a component requirement: verbal.

— Dan Dillon 👥 (@Dan_Dillon_1) February 19, 2020

I currently play an “oration bard”, in a 5e game, whose instrument is his voice. I never thought that wasn’t capable RAW, I just assumed the voice was the verbal component and he had material components like every one else.. As far as spellcasting rules go, that is correct.

— Dan Dillon 👥 (@Dan_Dillon_1) February 19, 2020