Because Iran, Pakistan, India, Kazakhstan, Russia, oh, and the USA would be so giddy over that?
Depleting what natural resources? All they have worth anything - other than poppies - is rare earth minerals, which China had already been about the only ones interested in extracting, and which would be far cheaper to do with the US babysitting the Afgans than China bearing the enormous cost of administering the territory itself, a cost which would far exceed the profits.
And of course, as you can't even seem to remember what you yourself posted yesterday, it was Trump that signed our withdrawal deal with the Taliban - no involvement with the Afgan goverment we've been building for 20 years whatsoever. Unheard of - a deal to hand over a country to terrorists we've been fightng to subdue for two decades.