The reason that the deepest human instincts abhor uncontrolled immigration and open borders is that we are all descended from people who practiced the opposite behaviours in the nation-state right down to the village level.
... but don't trust me. Manboons are not a learning animal and yet they always learn for themselves, when it is too late to do them any good.
What Rudyard Kipling called The Gods of the Copybooks always return.
Late era inhabitants of declining societies have something wrong with them. As suggested here many times, it has something to do with the amygdala and the development of the amygdala has an effect on the frontal lobes, known formerly as the "Seat of All Civilization." The pre-frontal cortex develops last and shares blood vessels that started their growth at the core of the brain, the amygdala. The prefrontal and frontal cortex never develop if the amygdala doesn't develop properly and in the left-wing the overwhelming scientific evidence says the amygdala is stunted. This explains why they can't recognize terrible hazards and danger when they are precipitating these things.
The left isn't just inferior in muscular strength, reaction time in the eyes and hands and the immune response. They are just inferior people, period. Every single metric in existence demonstrates it. When they achieve critical mass a civilization collapses. This happens around every 200 years on average, give or take a couple decades either way.