Why so few devices with BNC's??

"BNC is an acronym for British Nut Connector"

Incorrect.  The acronym is for Bayonet Neill–Concelman.  

Incorrect.  The acronym is for Bayonet Neill–Concelman. 

indeed...

https://en.wikipedia.org/wiki/BNC_connector#:~:text=The%20connector%20was%20named%20the,Paul%20Neill%20and%20Carl%20Concelman.

My Naim amps had BNC and DIN connectors.

A real pain in the arse they were too.

@charles1dad

Some of the absolutely best sounding audio components are utilizing RCA connection.

Agreed, but only 100%.

When Naim changed over to BNC's in the late eighties we used to call the Bloody Nasty Connectors. Nothing against BNC per se, but putting them on the phono section of Naim's preamps at the time when most Naim customers had Linn Sondeks with RCA tonearm cables was just sheer perversity!

@yoyoyaya

When later questioned on that decision, enigmatic Naim boss Julian Vereker would just say, we do it because we think it sounds better like that.

Naim were once an iconoclastic company, but in this particular case they took it too far.

After I eventually ditched the BNC/RCA adapters and got my Linn tonearm cable terminated with BNCs I was just a little disappointed to find that the amount of improvement in the sound equalled an absolute zero.

As Shakespeare might have said, it was all a much ado about nothing.

Thank you Julian, thank you Naim.