Economists might. Humans (of which I can only assume economists are not) definitely do accept the concepts of full and "too crowded."
> Everything we know about cities suggests that, in fact, quality of life doesn't go down as more people crowd in — the opposite happens.
[Citation Needed]
It's probably not, as you seemingly imply, that economists have simply modeled this up out of thin air.
you'd probably say Dhaka is too full at 112,000 per square mile, right? Well, why do humans live there? Indians are as human as any of us. Why would humans live in a city that's too full?
Because theyd still rather live there than the indian countryside. Even for Indians in Dhaka it's all about tradeoffs.
Written, no doubt, from a cozy brownstone in a high-rent district of New York City.