Yeah I guess, if you don't care about sustainability, pollution, the old vs young ratio (which brings societal issues such as retirement, healthcare, old age care), destruction of natural habitat, &c.
The "no rules" mindset is exactly what brought us in this position. We could be 30b actually, maybe more, there are no hard limits if you discard every variables...
The old vs young ratio is only a problem when you have fewer kids than previous generations. Which is why it is now being used as an argument for immigration.
Maybe it's violates another rule we like, and we can't keep both. If we posit that it's a positive thing that anyone in the world have unrestricted capacity to own a home, vehicle, pursue happiness and basically make use of resources as a Westerner does, then keeping the number lean could respect that - if the resource extraction, land encroachment and other externalities from demand become a problem at scale.
The fantasy from the greens is that Westerners are "consuming more and more". Really, there are just more people consuming.
I mean nobody creates the rules except us.