The impending collapse of Afghanistan shouldn't come as a surprise. And everyone's to blame. Everybody.
Why? Well, here's a thought - the US has been in Afghanistan for 19-plus years; the Soviets were there for roughly a decade. They - and the British Empire before that - thought that they could somehow take an intensely tribal, regionalized, backward society into the current century of their choice and make it behave as if any of the previous military interventions had actually worked.
They hadn't. And contemporary Afganistan is your proof.
From our point of view, no less than four American Presidents thought they could do what no one since Alexander the Great had done, which is change that region into something that it's not, or at least bring the Taliban to heel by military intervention (George W. Bush, Barack Obama until 2014) or by delusional "deals" he supposedly made with the Taliban (Trump). By withdrawing US forces, Biden is facing reality. The fact that that reality was hideously mangled by over forty years of civil wars, military intervention, constant butchery of civilians by warlords and different political and ethnic factions isn't strictly his fault. Instead, it's everybody's, going all the way back to 1978.
Granted, leaving what passes for Afghanistan's political "leadership" out of the blame game is equally daft. According to Transparency International, Afghanistan ranks 165th out of 180 countries in terms of political corruption. Add to this the fact that local military commanders decided to run for their lives or switch sides as soon as the Taliban rolled into town, and what you get is a collapse that was every bit as predictable as it was inevitable. What happens next is up to the Taliban and whoever chooses to fight them in the future, but what will probably happen is that the regime that holds onto Kabul will constitute the "government" and any number of guerilla bands and local warlords will constitute the real political power in the areas they actually control. And if the Taliban decides to shelter another group of Islamist lunatics who killed a shitload of foreign nationals elsewhere as they did with Al-Qaeda, the county will get bombed and invaded all over again. And the common people get to suffer the worst, just like they did in 1979 or 2001.
If Afghanistan ever manages to change - good luck with that idea ever being made a reality - it will be in spite of intervention by world or regional powers, not because of them. Pakistan, Iran and the like have reasons to keep Afghanistan in the current shape it's in, and Pakistan's military establishment in particular has no problems with the Taliban being in charge just as they were up until September 2001. The reality, however, is that the onus is on the Afghani people to fix things themselves. And when you've bottomed out as much as they have, the only direction out is to start to climb back up. Whether they can or not is anyone's guess.