IMHO it is not the breed but the potential harm they can do.
I kid you not people have been attracted by there Pomeranian or Silky Terrier (look it up) but you don't hear about it because no one dies.
I have had cats and dogs (mostly cats) and I have had cats go bonkers on me... now imagine if that had been a mountain lion. As beautiful as the lion is I would not want one in my house.
