Yeah, I wanted to give an example and disclaim redoing that specific discussion if possible. But just to provide a different view, what you're saying is fine theoretically, but in practice often people see the insurance situation as "some bad costly thing X can happen to me, I want to pay reasonable money to not have to eat the whole cost if it happens". Now if insurance companies had some super-accurate data and models on you (a futuristic perspective here), they could just infer if X will happen to you and take some free money if it won't and refuse insurance/make you pay everything plus premium otherwise. One similar case nowadays is health and old age pension, though these tend to be very regulated or state-run (i.e., tax funded). The point is that the scope of things where this applies can become very wide in the future.
Someone in the linked comment tree said "dispersion of the cost in wider population" is "not insurance, but a social solidarity scheme" and you may agree. But it's possible that we are currently running some "social solidarity schemes" only because of the imperfect information.
It would require more than imperfect information, but imperfect information _about_ the imperfect information. Ie, if people knew the insurance company had perfect information, they wouldn't buy the policy. At that point, the insurance company could just directly sell the information and still create surplus by reducing uncertainty.
This meta-imperfect information wouldn't last very long: People are generally skeptical of things like insurance as a baseline anyway, since they're unintuitive ("why am I paying for nothing every month?"). In this hypothetical world of perfect insurers, people would just sum up the anecdota of X insurance literally never paying out (and everyone rejected having X happen), and it wouldn't take very long for conventional wisdom to switch to "insurance is never worth buying".
Someone in the linked comment tree said "dispersion of the cost in wider population" is "not insurance, but a social solidarity scheme" and you may agree. But it's possible that we are currently running some "social solidarity schemes" only because of the imperfect information.