Photocopier salesmen were not driving around in AMGs...
True. But vehicles (and tech generally) has always been a game of top trumps in many respects, and 0-60 has always been the headline figure, daft as it may be. I don't care whether it takes sub-3s or 5s. Enough people do though, even if it's just for bragging rights in the pub.
Let's be honest, the performance capabilities of cars exceeded requirements a long, long time ago. It doesn't matter whether we're talking a 1100kg coupe or a 2300kg SUV, the principle is the same. They're faster than the vast majority of people could ever want, or be capable of properly using (I'm excluding the track here for obvious reasons). It's not much different to camera resolution/frame rate, or a whole plethora of other performance characteristics across different kinds of gadgetry.
Capitalism and economics don't just rely on what is needed. If it did, we'd be running around in modern day Trabants. The idea is to offer people things that they might want, or perhaps don't even realise they want yet (until they have it). Necessity doesn't come into it. If you're BMW, or Audi, or Tesla, and your competitor is outshining you on a particular characteristic of a product, then you'd better take sharp notice. It's not a good idea for anyone else to gain a foothold or advantage in a sector. It's essentially a technological and consumer-driven arms race, with no end in sight. Different companies vying for supremacy and market share, on a permanent basis.