That sentence is a tad bit disingenuous. What was the capacity in 1976 versus what it is now???? The existing plants have expanded and expanded and capacity has kept pace with demand otherwise we would have rationing and there would be 5 mile long lines to fill up. I filled up this weekend, no line, no rationing.
I think the issue is that our refineries have no EXCESS capacity and are running at very high rates of production nearly all the time.
To bring a refinery offline or reduce the output for maintenance and other things along those lines, a company is loathe to do do.
However, a fire or explosion in a refinery can wreak havoc on production and prices, but the reflection in what we pay at the pump is always somewhat delayed...