It does matter because oil is a global commodity, the fact that the US is a net exporter doesn't stop the prices from going up and other follow-on impacts to the global economy.

It means that US isn't hit the hardest. There's no "we have to end the war this month or our country grinds down to a halt". Just the slow grind of economic pressure that, I remind, affects more countries than just the US - and many of them far stronger.

US leadership can just say "this isn't enough to deter us" and proceed with the rest of the war however they want.