Evolutionary biology is much more complex than "survival of the fittest". How do you know that enduring and overcoming suffering does not enhance the gene pool? How do you know that the genes that cause anhedodenia are not one random mutation away from causing something entirely different? It could be that the survival of the gene pool is the only thing that matters and individuals or even generations don't matter one iota whether they suffer or not. See "The Selfish Gene" by Richard Dawkins.

Isn't the whole purpose of this forum to help each other find solutions and overcome depression? Sometimes acceptance is a part of that solution. Accepting one has a disease doesn't mean you don't seek to overcome it.