You’re really, absolutely, objectively wrong.
People who are supporting a candidate whose support is barely above the white noise probably aren’t thinking much about electability to begin with.
I keep coming back to how people react in just about any situation where they’re confronted with way more options than they can sort through. Two choices are better than one, and three choices are better than two.
But ten choices aren’t going to be better than five, among things it’s not straightforward to compare: people will look at fewer, rather than more. And when it gets up to two dozen, that’s why the Betos and Bookers and Klobuchars couldn’t get any traction, even after one or another of them did well in the debates.