For some reason, I can't highlight the 1st comment.

Trapping one's self into a box is harmful, and leads to the need to feed off of that identity to feel actualized. While I don't believe that setting a firm identity to yourself ultimately or always leads to self destruction, I see where z is coming from. On the contrary, a firm identity can allow people to feel as if they aren't drifting in space, and can give something they can hold onto. Especially in the case of a fursona, a personality (purrsonality?) and figure that is inherently extrinsic, but connected to one's base self, the human. This same logic could be applied to therians and otherkins, possibly even more so, due to the intense non-human identity associated with the terms, as opposed to members of the furry fandom, which may be participating in a more casual, removed fashion.