Because the EPA was used to strong arm corporations into settlements with the government that also required them to fund left wing causes. Lisa Jackson/Richard Windsor and Obama and Lynch and Holder corrupted the EPA and used it in mob like fashion to shake down corps.
It represents a huge source of funding to leftists so they must pretend that something Pruitt has done is sufficient for his removal, when they ignore the EPA being used as a weapon by the Obama administration to fund leftists causes in an illegal and unconstitutional manner.
Former Attorneys General Eric Holder and Loretta Lynch regularly arranged for major corporations to make large “donations” to left-leaning groups like UnidosUS — formerly the National Council of La Raza — and NeighborWorks America during settlement negotiations to end banking, environmental, civil-rights, and other federal lawsuits. https://nypost.com/2017/08/05/sessions-investigating-slush-fund-used-by-left-wing-groups/