I could go back to the beginning & find specialist racecars, but even sticking to "since F1" you'll find specialist endurance cars. Back then you could throw a plate on them & drive them away, but you could probably do that to a F1 car in 1950 without much more than sticking lights onto it. Off the top of my head, let's pick... the Jaguar D-type ( 1954 ). Can register one for the road but it sure wasn't built as a road car, it's about as practical as using a modern Radical. It did bring aerospace construction to cars though - this is what prototypes are historically for. That's why LMP-H was there in the first place, it was just horribly conceived.
BoP is ok in theory for privateer events - in those cases the teams are competing & quite a few of them will have the same car, which is why Blancpain works ok. In GTE-Pro and anything with pure works teams it just makes the event a farce, because it's the cars competing; what's the point putting a major amount of work into building a car when you can do a bare minimum & get the regulations to equalise it all? you can gain more on the track by influencing the politics than by good engineering. Porsche have been past masters at playing games with the rule makers, but at least in times past they've also had to do the engineering, hence the 917 and the 911GT1. There'd be zero point in something like the 911 GT1 now, because it'd just get hammered by BoP to bring it down to the others.
My concern with the new prototype class is they're going to say "here's a budget, build it to look however you want, we'll BoP it all at the end". What's the point? that's as artificial as just picking the race results with the BoP computer.
