> they just grow and grow and grow as necessary. 100x in 20 years if needed

Unless you want to have a livable city, and want nature nearby, yes sure, just grow, and grow, and grow. Btw, Shangaians f.e. want a word with you.

Perhaps Lisbon, as many other cities, should impose a limit on newcomers / population and area growth. It would help conditions and feel a lot.