The Task and Purpose critique was better, I think the author hit the nail on the head with this comment.

The biggest impediment to defeating the Taliban, a fractious and far-flung enemy, has never been an inability to kill its fighters, which U.S. forces still excel at; the problem has been figuring out what comes next, after the killing.
So even we do apply sufficient violence to clear an area of the Taliban, we can consolidate our tactical win into a political win. The reason in my view is our failure to understand the local dynamics, and we attempt to impose a Western idea solution that will never work, or at least for the foreseeable future. We need to adjust our ends, or we'll be in Afghanistan forever.

Long-term success in places like Afghanistan and Iraq requires a credible alternative to insurgency and sectarian conflict; it requires the building of central governments with legitimacy. This feat that has so far eluded the United States and its allies in Iraq and Afghanistan. Killing many, and often, hasn’t helped.
This feat will continue to elude the U.S. and its allies, so is it really a feasible course of action to achieve a win (however we ultimately define that)? This is simply COIN Kool-Aid, one size fits all, no analysis on feasibility required. All we have to do is establish a democratic government, provide some economic aid, and presto we'll achieve our ends.

However, this critique was much better argued than the previous one. It is unfortunate that the authors of the "Think Again" piece weakened a needed argument that questioned the conventional wisdom with unneeded bravado.