That is something I'd like to understand. When I was Mormon, the teachers of Mormonism just ripped at Catholics- called them the great harlot. Protestantism was seen as a movement their god allowed so his restoration Church would be acceptable. When I became Christian - I discovered what Catholicism was - one of us - Christian - one of the the first and essential in compiling scriptures. I honor the Catholic Church and share beliefs in the same God of the Trinity.
Mormonism is something different altogether - The Pope has officially recognized this - but yet, Catholics (especially here on FR) are doing whatever they can to protect Mormons and their bastardization of Christianity.
So it's easier for us to see the uselessness and nastiness of the mugging and to feel empathy for the muggees.
They were just trying too fit in with all the other kids. Nobody likes being different.
The Jehovah's Witnesses have a special place in their bile duct for us too.
Most Catholics I've observed on these threads are protecting Mormons from the bastardization of Christianity only insofar as shielding them from those (and you know who you are) whose behavior toward them is unacceptable. They recognize the witness to be lacking.