Humans aren't actually stupid/irrational. Most of the time when they say something stupid they're lying for ego reasons. Occasionally it's because you don't understand. (Though this itself is usually because of ego reasons.)
All that dumb stuff leftists say is certainly bad for non-leftists and society in general, but it's almost always reasonably useful for the leftist. E.g. gay marriage is fine because a leftist can't have a healthy marriage anyway. If they couldn't divorce it would in fact be worse. E.g. BLM of course kills blacks in huge numbers, but that means the leftists don't have to live around as many blacks, doesn't it? E.g. Trump reveals how inferior the leftist is, and it's much easier for them to hide their inferiority from themselves if he doesn't remind them of it all the time. It's all fundamentally competent...given their background of fundamental incurable incompetence.
"Alvin nodded. “I like that. Maybe the Questing Stones really are making things up as they go along.”
Wes cracked a grin. “Just like we are.”
Alvin laughed, lifting his mug of tea to the air. “Just like we are.”"
If you're making it up as you go along I hope you're 12, because otherwise it means you're broken/insane. However, given the assumption that you can't be an adult, pretending it's normal to have arrested development is rational. You can't un-mutate your mutant genes by thinking about it. Might as well pretend they're not defective.
That said, the correct way to deal with leftists as a society is to trap them in their own sandbox.
They have a desperate need for control because things that are slight inconveniences for you cost them 10-20% of their stocked capital; very serious. Have to be able to prevent that, right? You can deal. They cannot deal. Except leftists are incompetent and shouldn't be allowed to be in charge of a literal box of sand, let alone a functional social system. Hence, lifelong quarantine. E.g. huck homos back into the closet, except the gay district. There's no reason not to let them have a gay district as long as the gays stay inside and are harshly punished for trying to spread.
P.S. If someone is genuinely stupid there's no argument about it. Nobody mistakenly thinks the genuine moron isn't an moron. We're all sort of embarrassed on their behalf and try to pretend they didn't say anything.