There are plenty of diverging and legitimate opinions which are not fascist. Plus, the whole problem with fascists, their core definition if you want, is that they don't want to discuss. They want to crush and oppress. Debates are just rhetorics for them. So, you wrestle with pigs, and end up covered in shit. That's not a rational debate.

We used to think that was a good idea. But if the person is not actually trying to argue or discuss topics in good faith, but is simply exercising their particular side's propaganda, there is no value in them being there.

Obviously this is a grey area judgement call, but the difference is real. It is for the same reason that there is generally no point in inviting a serving politician on the panel, because they will reply to everything with their prewritten talking points, which you can get from their party's mailout or any of the press conferences given by their frontbenchers.

That's arguably how we ended up with climate change denial. Freaking platforming every Tom Dick and Harry with 2 misfiring brain cells to argue against the scientists and giving them equal attention.

The element you're missing, is that fascists have no need to honestly represent their ideas on the debate stage.

When you platform a fascist, you're just giving them a megaphone to lie about how they are actually progressive and left-wing but an immigrant took their job, so now we should round all immigrants up and deport them to Sudan.

BBC in recent years has (arguably maliciously when you look at some of the backgrounds of the recent show runners of things like question time) been presenting two views as equivalently valid when one is from a genuinely respected expert in whatever field is being discussed and another is from racist Barry from the pub who drove a leaded petrol car for a few too many years.

Presenting two sides as equal is not impartial, it gives extremists a platform to amplify their platform.

The paradox of tolerance follows that we should actively avoid platforming bad-faith extremists. Let alone presenting their views as reasonable.

That's what we did, and it just normalised their ideas