These cars are Icon cars so their performance is secondary to the actual joy of ownership. Old school Porsche 911s will be blown into the weeds by a 10 year old Jap rally rep worth a tenth of the price, doesn't make the 911 any less desirable.
Never driven any Cosworth but I'd like too. I tried to convince myself I like the Sierras when I had the cash to buy another Impreza but I couldn't do it.
Esc Cossies were limited in build and highly sort after yet they didn't really do anything the sierras didn't - same with Imprezas, A P1 doesn't really do anything a normal STI (from V3 onwards and even then it would struggle against a decent V3 STI) yet it commands twice the price. Same with Lancia Integrale, same with just about any marque that brings out a special edition that is loved by enthusiasts. Its an enthusiast tax.