When did it become ok to bully??

When did it become OK to bully someone for their opinion? I was on a group yesterday on Facebook and posted a comment. I started out by saying "This is my opinion" Meaning this is what I think. I just commented that I thought an actress that was cast, was the wrong choice. That she looked just like Jennifer Love Hewitt. Why the heck wouldn't they just try to cast her. ( I know Jennifer Love Hewitt, is in another show.) That this then when I got not one but two rude comments. One telling me I am not classy for my statement. Then one that was past the point of rude. Calling me a bitch and calling Jeff a pediphile? huh? As if attacking me for my statement was classy? I am thinking What the F--K? I got over 6 likes, so I know I am NOT the only one thinking this thought. I just don't see how me saying this casting choice is wrong, should have people making personal attacks. Also the show in question has been on the air way past it's prime. If a show gets to the point when you want to punch or shake the main character because all they do is wine and complain, it's time for the show to be pulled. I am NOT going to bother wasting my time on this show in the future. Or posting my thoughts in any more Facebook pages or groups! Unless I have posted there before and know I will NOT be attacked.