I don't know if you mean that counterinsurgency efforts generally fail, or that SOCOM generally fails at them, but neither is the case. In Iraq, COIN is a catch-phrase that gets a lot of lip service, but is not really put into practice. There's too much top pressure to get results fast, and very few advocates of doing it right. Green Berets in Iraq are used more for direct action mission than they are getting into communities and training new troops, and the higher teir SOF is exclusively playing whack-a-mole.
Before Iraq, I spent a good deal of time in the southern Philippines, which was a great counterinsurgency success in breaking support for the Abu Sayyaf Group within the local communities themselves. There's great FID and COIN successes all over the world, keeping the lid on simmering problems. There won't be a similar level of success in Iraq and Afghanistan precisely because it's the Big Army running the show, not SOCOM. Big Army is too traditional, clumsy, politicized, and heavy handed to do it right.
In any event, my point remains that SOCOM is not meant to be limited to counterinsurgency measures, MARSOC's operating doctrine was not based on counterinsurgency nor did they claim it to be, and they were not asked to come to Afghanistan to act in this regard. They were to be a kinetic resource at the disposal of the counterinsurgency force, a mission with little or no nuance. The story was that the Special Forces in the area felt (for exactly the reasons you listed) that they could not strike definitively where their dealings with the tribal warlords would be jeopardized. They were brought in to be bad cop to Special Forces' good cop. They were given unprecedented partnership with the Nightstalkers to this end (which to my knowledge is not given to say, the SEALs).
Their first engagement was the aforementioned ambush of a convoy, with a vehicle borne I.E.D. and small arms attack from two locations. Respectfully (as it is obvious that you know far more than I do on the subject), how would you have dealt with this situation? I can appreciate nuance in planning and in communication with the population, but we are talking about bullets flying now. What would the Green Berets have done differently here?
I can understand being the devil’s advocate, but I am trying to get support for the Marines whose careers are ruined and who are at risk of prison for fighting off an ambush. I really don’t think our debate is helpful to that end. They were asked to go, they went, they fought, and they may go to jail for following their SOP.