>You may perceive many opinions as invalid, but you don't know how people arrived at them - from their perspective, they're perfectly valid.
Of course. But this has no relationship at all with their actual validity.
>a sign of respect and understanding that information processing is difficult and that we acknowledge that the opinion is reasonable from their end.
But it's not about opinion, it's about the effect of those opinions on other people.
I don't really care if some people think the EU is an organisation of Satanic Communists who plan to take over the world, and that Britain has been cheated out of its empire and self-respect by EU membership.
They're perfectly entitled to their opinion, even if I think it's nuts.
I most certainly do care if those people have the political effect of depriving me of my right to travel and work in neighbouring countries. Then it's no longer just about opinions, but about someone imposing a crazy world view on other people and having a real effect on their lives.
The opinions can be dismissed. The political effects can't.
And that's the real problem. Free speech doesn't just mean the freedom to criticise the government - it also means the freedom to try to persuade others of the validity of a point of view, and to convert that persuasion into political power.
Which is a problem, because it allows bad faith actors. Currently as a voter I have more legal redress if I buy a toaster and it stops working than if a politician wilfully and knowingly lies to me during a campaign of persuasion. Similarly, there is very little redress against media outlets that lie or make up content to further a political agenda.
I'd suggest both of those need to change. The action of deliberately and knowingly misleading the public should be not be protected by free speech laws. Politicians and media companies that do it should be held accountable.
The rationale is simple - professional liars benefit no one except themselves. There is no case to be made for allowing wilful, deliberate dishonesty in public discourse.