If anything, it only empowers the critic, and gives their review more weight (and attention).
Or even better: write a play about them.
Tom Stoppard's excellent The Real Inspector Hound (which The Publick will be performing in the fall at the BCA) is a great example of a playwright writing about (and alternately humanizing and savaging) critics, as is Conor McPherson's St. Nicholas, a terrific one-person play the Sugan produced years ago, about a theatre critic who falls in with a troupe of actors who are really vampires.
The truth is, we NEED more people writing about theatre, who care about theatre, who are passionate about it, who want to start a conversation.
Even if we don't always like to hear what they have to say.