Because if you give an inch to that line of thinking, it leads to broader dehumanization and mass tragedy.
No matter how noble your intentions are, if you reject science then you're anti-science. Leftists need to learn to admit that about themselves instead of trying to have their cake and eat it too.
What is true is already so.
Owning up to it doesn't make it worse.
Not being open about it doesn't make it go away.
And because it's true, it is what is there to be interacted with.
Anything untrue isn't there to be lived.
People can stand what is true,
for they are already enduring it.
(Eugene T. Gendlin)