Jabawocky, whilst I know and understand what it's like to operate in a congested zone where the radio chatter can become chaotic, I would be alarmed to think I might be making radio broadcasts to pilots who willfully turn down the volume and don't hear them. Whilst carriage of VHF radio may not be mandatory at a CTAF, the regs still state that - if carried - you are expected to use it. At least that was the case last time I had a look in the books.
As frustrating as the chatter can sometimes be, it's up to pilots to learn the art of filtering through it all to make sense of what is being said.
Not passing judgement (as I wasn't there), but would not want to encourage the idea that it's ok to switch off when you get sick of listening to the frequency.