nostr:npub1syf88qrutdky8hl7f63s8sznazrr4pehcp9nlpnfqffkz6ptpr2ssqmzey 
1 not enough surface area
2 the part wears over time
3 it's easily replaceable with aftermarket
4 brass catchers have been a thing for a century
5 nothing stopping anyone from dropping random range brass at crime scenes 
6 there are over 500,000,000 guns already owned by civilians in the USA that won't have this.