While I agree with her points, it seemed like she really was preaching rather than investigating (at least for the first five minutes that I watched). Her questions were leading questions of the yes/no variety where she already knew the answer. I think Stumpf needs to be held responsible beyond resigning (canceling his golden parachute would be a good start). But I think Senator Warren should either give a speech or ask honest questions, but not give a speech disguised by a veneer of questioning.
Nothing personal against Senator Warren, I assume this is de rigeur for Senate hearings.