Thank you for post. Interesting subject.
I was in the wholesale hardware distribution business for 40 years. Observed a lot of strange things related to brass in plumbing.
40 years ago, brass valves were the norm, not so much today. I have seen brass harden and become brittle after years of use in very hot water (mixing valves). I suspect the zinc content is leached out and the brass is even more red than when the faucet was manufactured. I have seen mixing valves where the Hot water side was noticeably more red than the cold water side.
Plumbing was very simple 50 years ago, faucets lasted longer and could be fixed easily. Today there are some great valves with very little brass in them, but there are so many different variations in how they work, it is hard to repair one.
TF
If it's too easy to repair, they don't get to sell as many new replacements.