I think you're making your own counterargument: if you prioritize civil discourse, you necessarily exclude radicals - you've limited the space of discourse by insisting that the only acceptable propositions are those that people can reliably be civil about. Fewer people were making extreme claims, but many of those extreme claims
could have been debated rationally, were people interested in doing so. It is a Potemkin discourse: it looks very peaceful and respectable, but it looks that way because it's artificially removed from actually discussing the state of our society.
So, I am happy to engage you in debate, and I'll even do your job for you by trying to precisely name the propositions that you think are so obviously incorrect.
Most of the hits I see for "milk is racist" is about the alt-right using milk drinking as essentially an aesthetic symbol, which seems like a) a factual observation b) not a claim about milk itself being racist, but about its adoption as a racist symbol.
I see a 2016 CNN article called "math is racist," which, if you read it, is clearly arguing that mathematical models are being used in ways that reinforce racism, not that the brute facts of mathematics are themselves racist, either. This argument is generally widely accepted, so I'm curious if you disagree with it.
I can't find any articles about interior design being racist, but I do see articles about the interior design industry confronting race problems. This doesn't sound surprising or extreme either - I'd expect that most industries have race problems of some sort.
You'll note that I have not called you bigot, racist, fascist, nor xenophobia [sic], and I'd appreciate if you returned the favor and engaged my arguments on the merits.