Well, even Indy had to tone down the cars for places like Texas Motor Speedway because the drivers were passing out in the corners. Daytona and Talladega are run with restrictor plates in NASCAR for much the same reason.
The cars have been able to go faster than drivers can handle for a long time.
Nascar put restrictors on the car because they were hitting 212 average laps. And Nascar was not comfortable pushing the cars or tires (Nascar had open tire competition back then) farther than they wanted. so the solution was limit the amount of air an engine could take in. which created massive packs that cause 30 car wrecks. In my opinion it's probably killed more people than the cars running at 212 would have.
Rusty Wallace did 228 mph at Talladega Superspeedway without a restrictor plate in 2004. The new car probably could do a bit more than that. Racing at that speed would be insane and all the safety advances since wouldn't be effective. Further, they were implemented because Bobby Allison crashed into a retaining fence at around 210 mph. This is big no-no in NASCAR because fan's shouldn't be in danger[1]. Looking at what has happened in other series to fans at high speed needs to be a consideration.
I don't think a race at 228 mph would be safer than a restrictor plate race and I am pretty sure it would kill more people.
1) look at all the attention to the Nationwide Race where the catch fence failed
smaller engines for one, maybe even make them production based. Part of that goes back to relevance to road cars. I test drove a Fusion when I was car shopping. needless to say a pushrod V8 was not one of the options.
The cars have been able to go faster than drivers can handle for a long time.