The point isn't even really about libertarian ideology; it would've been about having a president better than Donald Trump or Hillary Clinton, as both Johnson and Weld undoubtedly would've been. Weld would've been a stronger candidate than Johnson because Weld could've secured in Mitt Romney's backing in June or July, prevented the whole McMullin thing from coming about, and used the added notoriety to be able to make it into the debates (even Johnson briefly hit double-digits in the polling average in August; Weld was much more charismatic, a better speaker, and could've had much more powerful friends; he would've made it).
At that point, well, Weld has always been a terrific debater, going back to the Massachusetts days. I doubt he could've won the election (though the possibility isn't excluded), but he could've at least made it an actual three-way race.
Weld was the wrong tool for the job. (in more ways than one) The LP needed to run a Bernie-style insurgent campaign, and the problem with Johnson choosing Weld was not only that he wasn't a libertarian, but that Bill Weld is the guy you call when you need to put on the fishnets and get on your knees for the donor class. They treated the election like a resume contest and thought voters and the media would respect them just because they won a few gubernatorial elections back in the day. Plus, there's no way Weld at the top of the ticker could've carried the baggage of the LP's insane anarchist base, like the videos showing them booing driver's licenses or laws against selling heroin to children.
Johnson was a terrible candidate, but I doubt anyone could have done better as a Libertarian than he did.
