IMO Removing/merging repeated questions is important to keep up the standard of SO and is what makes searching easier in the long run. I agree that comments sometimes can get very picky and discouraging.
I agree it's important, but if I had a dollar for every time a question whose answer I also needed was marked a repeat of a similar (but not identical) question with an answer that was invalidated by that discrepancy, I wouldn't need to use stackoverflow any more.