I think that provides much more effective oversight of risk allocation than any regulation.

No, it didn't. Did you miss the part where Lloyds imploded, and the unlimited liability destroyed scores of lives (and caused multiple suicides)? The 'reinsurance spiral' certainly was not effective oversight. Even counting the Names' net worth, Lloyds had less reserves and greater risk exposure than regular corporate insurance giants that it competed with, like Swiss Re and Munich Re.

EDIT: It occurs to me that the obvious rebuttal is that Lloyds was quite profitable for a century or two, and so we shouldn't hold the asbestos disaster against it. But it seems to me that any fool can capably insure against risks that eventuate every month or year; high quality risk management is known from how well the extremely rare events are handled.