I've seen a lot of "liberals are doing it wrong" kind of things about how DeVos was not the worst cabinet appointee therefore it was wrong and maybe even sexist to focus on her. Of course liberals don't get their marching orders from George Soros central (hey, George, your last check bounced), so it isn't as if there's some grand strategy involved. Grassroots opposition catches fire for reasons that central casting can't always determine. If I were your Resistance Leader I wouldn't have prioritized DeVos as the all things considered worst Cabinet nominee, but there was certainly the case to be made that she was both 1) bad enough and 2) most likely to be rejected.
If I could've picked one appointee to fail I would have chosen Sessions, but there was little chance a bunch of Republican senators would vote to block one of their own. There are a couple of others who are probably worse, all things considered, than DeVos as well, but good luck getting a grassroots campaign about the Treasury Secretary.
Kids. Education. Inexperienced billionaire twit with horrible confirmation hearing. People understand this stuff and how it affects them. It isn't that complicated.