Reviewers are usually people who would have been, poets, historians, biographer, if they could. They have tried their talents at one thing or another and have failed; therefore they turn critic.
It is the beginning of all true criticism of our time to realize that it has really nothing to say, at the very moment when it has invented so tremendous a trumpet for saying it.
It's useful for activists just to be out there to keep you mindful and not get complacent, even if ultimately you think some of their criticism is misguided.
There is a difference between responsible criticism that aims for success and defeatism that refuses to acknowledge anything but failure. Hindsight alone is not wisdom, and second-guessing is not a strategy.