Damage to public / private property is normal in a riot, that's where riot police comes in - who are, on paper, experts in nonviolent / nonlethal crowd control and de-escalation. Deploying the National Guard would have been an unnecessary escalation.

I do wish either riot police or the National Guard was deployed on Jan 6th though. But neither Trump nor anyone in the chain of command with that authority did, which only emphasizes how it was orchestrated and intentional.