They might open themselves up to lawsuits. Even if they will win the lawsuits, that's a money/time sink to deal with.
This seems to avoid the defamation issue because it is a personal statement (about yourself / your thoughts) instead of a statement about them. They could still sue you for defamation, but hopefully you could get it thrown out early at a low cost?
Not everyone has $50k and the time to fight a libel/defamation suit.
No, but that's part of what would be at issue in a lawsuit.