Having grown up in the days of the roadsters popping up, I can say they were very quick, but they failed to win everything. Of course we are talking a time when a guy who ran a local garage would cobble together something and go racing. It wasn't a deep pockets deal like they are today. I recall a guy named Harry Turner who built some remarkable race cars that were far and away technologically advanced and didn't beat the pants off everyone. The whole history of open wheel racing has been constantly moved forward by tinkerers and doing things differently. One offs, and short run machines are always there. It wasn't so much that one car dominated that ruined the racing, it was more a case of the sanctioning bodies stepping in and taking direct action to stifle the ingenuity that was coming along. Making the cars all the same, use of wider tires, high horsepower motors and exotic metals has led to increasing costs and lower car counts than anything.