It used to be that those guys were on the fringes of the party. Nixon was a crook, but he established the EPA and OSHA. That was just a normal thing for a Republican to do in the 1970s.
The GOP is a big tent party, and so they’ve always had room for the extreme right wing. These days, the tent is getting smaller, and unless you’re an out-and-out fascist you’re not really welcome. Unfortunately, half the country feels a stronger tie to that party than to their country, so they’re squeezing into that smaller tent.