O why do I ever let anyone read what I write! Every time I have to go through a breakfast with a letter of criticism I swear I will write for my own praise or blame in future. It is a misery.
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.
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.