I think in both cases fear comes into play.
Fear of the unknown powers an awful lot of arguments and attacks.
For instance take a devout Christian with no prior knowledge of Kindred and tell them you are a WereCat.
If they do believe you they are very likely going to feel that their faith and world has been threatened by something they do not understand.
If they don't believe you they are likely to think you are just plain nuts.
Some of the people on Otherkin sites do not like to think that anyone is as different as they are or that any other otherkin exist or that anyone knows more than they do.
So anyone who says they
are Kin or tells it, how it is, or comes across as being confident and at ease with themselves and everything else, instantly becomes a threat to that person.
No one is allowed to be as good at it as they are......
Unfortunately the truth is that usually people like that are really quite sad and trying to look important instead of help people like themselves.
Zygo