Look at the types of cars people drive for an everyday demonstration of this fact. The majority of cars on the road are optimised to carry a reasonable load, at a reasonable speed and with reasonable fuel consumption. Evolutionary (economic) pressure has resulted in moderate increases in performance, comfort and safety, but we are not all driving around in cars that are hyper efficient and capable of 100mph+ performance while using a teaspoon of fuel per mile. We have gas guzzling monster 4x4 off road vehicles, exotic sports cars and small efficient city cars, but the majority of vehicles on the road fall into the distinctively average category.
I'm not sure I buy that argument entirely. Yes, the non-specialist compromise design might capture a major chunk of the market. But that doesn't mean that the niche market doesn't exist: Monster cars are being sold for decades. So are RVs & bulletproof cars & gigantic mining earthmovers.
There's a tiny market for a gigantic transport plane or the behemoth seagoing barge that can transport mega machines. But doesn't mean that's a dead market or money can't be made there.