Words change over time. In this case they were co-opted and purposely made ambiguous/muddied. People love to change the meanings to suit their goals.

You're even doing it yourself. A centrist does not always vote democrat for the safe choice. You're describing a modern leftist. They vote the safe choice, doesn't matter if democrat or republican.

Notice you have to prefix leftist with "true" just to emphasize you're not referring to the modern variant.

You're confusing leftist with libertarianism. Libertarians today are now conservatives and leftist are now authoritarian conserv... No not conservative, they're a new special breed. The conservatives you likely think of are now branded the "far-right" or "alt-right".

Centralists do not want authoritarianism. What your referring to as Centralists is now what's called a leftist.