It only has traction because it's a gross oversimplification that appeals to those that seek simple answers to complex realities.
"The answer" isn't somewhere in between white nationalism and Universal Basic Income, for example. Centrism is a ridiculous ideology. It's honestly more of a lack of any coherent ideology at all.
The centrist ideology is "I'm above a consistent ideology - things are too complex, so I'll smugly dismiss everyone as wrong while I stand for nothing, have no discernible values, and no solutions to anything."
The alternative (and usual practical outcome), is that they're just hiding strong right-wing tendencies behind the flimsiest of veneers. I'm looking at you, Tim Pool.
Horseshoe theory: a bunch of bullshit invented by ideologically deficient people to make themselves look good while lumping in leftist reform advocates with fascists.