Simple. They sought out opposing opinions, even had people on their staffs with opinions contrary to their own, in an attempt to develop programs for all America.
Conservatives can nitpick, logic-chop and wiggle all they want, and can’t change that. Imagine a committee member who disagreed with Cheney.
FDR did try to pack the Supreme Court, he didn’t want opposition everywhere, but he understood opposing positions.
Interesting, huh.