you are right, but that was a time when people were less concerned by the cost of fuel and the emissions regulations were non existent, catalytic converters were the chaining point, namely cat preheat, a lazy V8 from cold does not create enough heat quick enough to activate the cats, this means that you have to have very clever control on valve timing and fuelling (hence why we have port and direct fuelling) but effectively you are burning an excessive amount of fuel just to generate heat to activate the cats, which is pretty counter intuitive. Also start stop is a nightmare on a V8 due to its rotating mass
there was a time when nearly 50% of Range Rovers were V8s, they are now less than 10% with a large proportion of those being SVR variants owned by people that earn far much more than the common man, the market is just not there