It is an interesting and pervasive issue. Congress delegates power to a commission or agency, and sometimes the rules (which are a step removed from the law) become the sticky point. It is very real that the executive writes plenty of law. Not just regulation, but also legislation that is put in the hopper by a cooperative congress-skunk.
Like sunlight, garlic or a cross to a vampire, one thing that congress avoids as much as possible is accountability. Congress could clear this mess up - it passed it, including the parts that enable and circumscribe the regulation creation power.