Hmmm, guess you missed the early 90s of IndyCar racing where you had Lola, Reynard, Swift, Penske, etc. building their own chassis and Ford-Cosworth, Chevrolet, Mercedes-Illmor, Toyota, Honda building chassis. Teams would show up at Indianapolis with special-built chassis like the Menard and engines like the Buick. NASCAR uses 1 chassis and 4-5 engines with minute differences. IndyCar uses 1 chassis and 2 engines. F1 isn't that bad yet, every team has to build their own chassis though half the teams are using Renault or Ferrari engines.