As a libertarian with Yvain's hatred of noise, I may have some insight on why this is a dissatisfying answer.

So as long as it is clear who has the relevant property right (to make noise or to stop noise) they can plausibly make a deal to achieve the efficient outcome, at least if the problem is big enough.

But people can't quite anticipate all the ways that others can be jerks[1] and will therefore assume certain rights which other people, by will or accident, can find holes in: the relevant rights weren't defined like one might think.

So, as I've ranted on my blog, imagine that it just so happens that your neighborhood doesn't prohibit the level of motorcycle noise that is just enough to drive you batty. Then, I come by and rev my motorcycle near enough to your window to annoy you, but not violate your rights.

No problem, right? You "just" pay me to go away. Problem solved.

Er, until the next biker, who hasn't sold his right to you, comes by and extorts -- that is the right word for it -- from you the same way. What next? Do you buy out everyone in the world? Do you sell your home? Well, who's going to buy the house with the Harley extortionists?

At some point, Coasean bargaining breaks down and becomes extortion. I have a neat graphic for this too. Go here, scroll down, and replace "pollution" with "loud noise". (And maybe "Bob Murphy" with "Robin_Hanson"...)

[1] Okay, okay, people with different psychological impressions of stimuli.