What's the point of the new Ted Cruz birtherism?

Brand new year, brand new resurgence of one of the more frustrating and futile political firedrills out there: Ted Cruz birtherism.

The ringleader is—shockingly!—Donald Trump, who reopened the old controversy about whether Cruz is eligible to be president, given that he was born in Canada, in an interview with The Washington Post:

Republicans are going to have to ask themselves the question: “Do we want a candidate who could be tied up in court for two years?” That’d be a big problem. It’d be a very precarious one for Republicans because he’d be running and the courts may take a long time to make a decision. You don’t want to be running and have that kind of thing over your head .… I’d hate to see something like that get in his way. But a lot of people are talking about it and I know that even some states are looking at it very strongly, the fact that he was born in Canada and he has had a double passport.

To get a few things out of the way: First, it is not true that Cruz “has had a double passport.” There’s no such thing—though Cruz was a dual citizen, apparently unwittingly, for years before renouncing his Canadian citizenship in 2014—and Cruz says he never held a Canadian passport.