Performance car /= sports car. Sports cars are light and nimble by definition. They are usually fast, but this is not a rule. There have always been sedans that are faster in a straight line than most sports cars. There have always been sports cars that are not very fast at all. None of this is new, and claiming otherwise is ahistorical. Even back in the '60s, a sports car enthusiast would have chosen an MGB over a much faster Camaro, because the MGB is a sports car and the Camaro is not.
Engagement, dynamics, and "feelsomeness" are not vague at all. Handling is the product of engineering. It is largely objective. Some cars really are easier to control than others. Some really do hold on better in the corners. Cars really do have more or less body roll and more or less oversteer. What "character" is best is a matter of opinion, but the car really does have that "character". The fact that something is hard to measure does not mean it doesn't exist.
Sports car fans mean exactly what they say: they value handling over acceleration. If they didn't mean it, they wouldn't buy sports cars.