They never have been, the appeal of a populist with strong convictions is not some new phenomenon, it's literally every notable, charismatic leader in history (good or bad).

Centrism is purely about the fear of being blamed for an adverse outcome, and hewing to the least 'controversial' path as a result. It's even telling, because by definition Centrism has no fixed ideology; if a country has 2 fascist parties, then centrists by definition lie in whatever light exists between those 2. I use that example apropos of nothing, of course.

The Democratic party has been pulling us all right hand in hand with Republicans. This isn't an oppsie, it's by design. Establishment will always push right using "centrist" bullshit. There's no left in America, only right and far right.