With oil think globally, not locally. Disruptions in oil supply would have a huge impact on Europe and Asia. Would slam financial markets. Everything is connected. By the way oil is priced in Dollars. If the U.S. didn't police the Middle East oil might get prices in Euros or something else. That would severely devalue the Dollar. They'll never let that happen if they can help it.
100% The modern global economy is too interconnected for areas like the Strait of Hormuz to be blocked off without everybody taking a pretty big hit including the US.