I called it naive because I believe it is an oversimplification.
Strong Towns has an agenda (which I mostly agree with), and in order to promote their agenda they have a straw man argument that broadly categorizes _all_ suburban development as an unsustainable venture that is borrowing against the future.
I agree that there is (in many cases, but not all) some deferred costs and externalities that are not being fully accounted for in new development.
However, I'm not nearly so pessimistic as to think that the people living in those developments won't make changes to account for those deferred costs and even possibly some of the externalities.
And the Strong Towns write up that has links to more reading that I believe informed that video: https://www.strongtowns.org/journal/2020/8/28/the-growth-pon...