The problem with “I’m entitled to my opinion” is that, all too often, it’s used to shelter beliefs that should have been abandoned. It becomes shorthand for “I can say or think whatever I like” – and by extension, continuing to argue is somehow disrespectful. And this attitude feeds, I suggest, into the false equivalence between experts and non-experts that is an increasingly pernicious feature of our public discourse.
Everyone can have an opinion. But having an opinion is not the same as having truth on your side. If your opinion is wrong, than it should be thrown out of any argument as worthless and distractive.