Different grades of crude refine to yield different percentages of products. Refineries are engineered for certain feed-stocks to maximize certain product yields. Putting the wrong grade of crude in the front end would skew the yield of the valuable products and generate waste products.
Gulf coast refinery set up for Venezuelan heavy have sourced other heavy oil from Canada to compensate for the decline of PDVSA. U.S. exports some light bodied shale crude to European refinery. Some is blended with other crude oil sources. It’s a balancing act.
The solution is to screw the US consumer and not refine the lighter stuff here. I get it.