There are some other things transpiring in American politics right now. But we must note that Democratic leaders are now unabashedly stating what Bernie Sanders supporters said over and over in 2020: the party pushed Joe Biden primarily to stop Bernie.
The wiki page specifically says that it’s highly criticized:
Several political scientists, psychologists, and sociologists have criticized the horseshoe theory. […] political scientists do not appear to support this notion, and instances of peer-reviewed research on the subject are scarce. Existing studies and comprehensive reviews often find only limited support and only under certain conditions; they generally contradict the theory’s central premises.
Just because it has a wiki page does not mean it’s a valid theory.
The wiki page specifically says that it’s highly criticized:
Just because it has a wiki page does not mean it’s a valid theory.
https://en.wikipedia.org/wiki/Flat_Earth_Theory