Oh, bullshit. Bullshit, bullshit, bullshit.

That's because when people think along those lines, they are thinking in a linear left-right dichotomy which is incredibly limiting and doesn't fully explain political spectrum's. To properly understand what horseshoe theory is trying to explain, you have to think is a multi-axis system. Like this, because there is more than left-right, but left authoritarian-right authoritatrian, just as an example. For further reading, please examine things like the Nolan Chart.

lazy centrists who want to feel superior about their milquetoast ideals without having any actual knowledge about left or right politics

Wow, such an opinion completely discards the idea that a centrist can take a look at ideas on the left and right and decide that some leftist ideals are good and some are bad, and the same with the right. Or that they have come to the conclusion that being far to one end or the other usually fails to take into consideration a pluralistic and varied ideology among the population, and in order to enforce those ideals begins to become draconian and authoritarian.

Seems that your opinion of centrists fails to consider that maybe people aren't being lazy, but have come to a reasoned, nuanced opinion of government and social policy. Therefore, it's lazy thinking on your part to believe that centrists are lazy for believing in the horseshoe theory which wasn't written up by some chucklefuck on 4chan but by educated and intelligent political scientists who have dedicated their lives to studying the way humans try to form governments.