I think that's generally false. Policies are generally written to cover a broad set of risks (which would include riots, terrorism, and acts of war) and then have exceptions listed specifically. It would be rare in my experience for property insurance to itemize the types of losses they cover.

As an example, my policy covers general losses arising from physical damage, but then explicitly excludes losses from earthquakes, floods, oil spills, and acts of war.

If I buy only that coverage and a flood or earthquake damages my property, it's not my insurance company's fault that I'm not covered.

What I'm saying is obviously true. What you seem to be concerned about is that you think the premise is false. If that is so, you haven't really communicated that...

If an insurance policy covers all physical damage perils and riots are not mentioned as an exclusion, then riots are covered. It's not like physical damage coverage itemizes every possible source of damage and those that aren't listed aren't covered.

I'm literally not understanding your claim, so it seems like we are indeed having significant difficulty communicating. Because of the way contracts are written, I think your claim is pretty close to obviously false.

Concretely: if riots are not covered, it is overwhelmingly likely that the contract will be structured as "physical damages are covered except as listed below" listed below: "riots are not covered"

If riots are not covered then they are not covered. It's as simple as that.

I'm just saying you're making a whole lot of points without actually addressing the literal contents of my message, which would make this conversation much smoother because otherwise we are speaking past each other.

It looks like that presumption is wrong because riots will be covered under the umbrella of "physical damage" but you haven't really explicitly made that point by addressing mine, so it's hard to move forward with you to a productive conversation.

Yes, if riots are not covered, they're not covered, but that will generally be obvious to the purchaser of the insurance (specifically by virtue of a clause about riots being excluded being present in the contract, in contravention to your claim above that "the clause [about riots] won't be in any contract to begin with". It will be there as an explicit exclusion.).

If the purchaser of the insurance makes the choice to purchase insurance which obviously and explicitly does not cover riots, they ought not be surprised when riots are not covered and it's not the insurer's fault.