The far right and left are always going to be homes for extremists, by definition.

And also practicality. Extreme people are highly motivated to push their agenda, and that requires a party. They adapt and find a way to participate, one way or another. Often simply by ramping up awareness of the opponent party's inevitable extremes.

The real question is: how do the moderates in a party operate, and are they currently tolerated and reasonably well represented within the party.

(I am using extreme here to mean a lack of operating in objective reality, or a strong will to divide who "matters" from who doesn't. Usually they go together.)