Why? I only have to look on the pictures to "get the picture" !
No, you didn't get it. You said you can continue getting parts for old cars. So what? Getting parts recycled from totaled vehicles is not quite the same thing as buying genuine parts from the original manufacturer.
Neither is buying parts from third-party manufacturers. Sure, you might be able to get parts made by third parties at some surplus auto parts store for a 1955 300SL, but that's the equivalent of installing FireFox, Chrome, Opera, etc. on XP. What you're doing is the equivalent of asking Daimler to start producing parts again for that 300SL.