Exactly.I actually think it is the other way around:
If the Afghan government and military put on a good show and it took the Taliban 2 or 3 years to take Kabul? = the US should have done more to help and they would have been ok
Kabul overrun in a matter of days? = if that is the result after 20 years, there was nothing that we could have done to change the result. They were going to surrender in 2, 5, 10 years from now
It was just like with Nixon's 'Peace with Honor,' private assurances that never happened under Ford.
The only thing I will point out is that when Trump-Mattis were exploring a treaty with the Taliban, the US Media roasted them.
In reality, it would have been far better than this.