"I cannot believe that there are people who advocate radio silence"
I think you'll find that most people advocate using the right frequency at the right time for the right reason. Sticking with the Oxford area as an example, there is no "right" frequency in Open FIR. Therefore, if you're in a glider with a poor (if any) radar return) and you decide to talk to, say, Brize Radar then you could be about to share the same bit of sky as someone else talking to Farnborough LARS, Benson Radar or Kidlington - none of whom wil be co-ordinating with each other for the big picture. So, as a glider pilot I'll stick to one frequency (130.4) when cloud flying as I know at least that all other gliders in cloud will be on the same frequency. I don't however know which frequency to use if there's power traffic attempting to share the same Cumulus - and the odds of getting it right are perhaps 4 to 1 (or worse).
There is definitely a mindset difference between glider pilots (don't talk to ATC/airfields unless necessary) and power pilots (speak to everyone). I accept that each approach works for its respective community.
Fundamentally though what is going to decrease the risk of collision in VMC .....talking to people on the radio or encouraging everyone to improve their lookout skills ? Neither is 100% guaranteed to provide 100% safety but I know which one I believe will make the most difference.
PS: Techie note on <quoting> in PPRUNE - Clicking on Reply and removing the '1' at the end of the NOQUOTE=1 in the URL works providing you're not using a PC that's within a corporate firewall that does URL checking. Also, have the same problem clicking on the reply button - no quote button appears....d'oh!