Because a lot of aftermarket valve cover have thin rails and leak, so this way you get to dress up the engine and have all the factory provisions etc. And have factory valve covers that don’t leak.
In a bone stock application it’s pointless to put tall valve covers on something and have to deal with clearance issues, baffles and pcv valves which a lot of times you make your own holes.
In a bone stock application it’s pointless to put tall valve covers on something and have to deal with clearance issues, baffles and pcv valves which a lot of times you make your own holes.