OK, I hope my question doesn’t get misunderstood, I can see how that could happen.
Just a product of overthinking.
Idea is that we can live fairly easily even with some diseases/disorders which could be-life threatening. Many of these are hereditary.
Since modern medicine increases our survival capabilities, the “weaker” individuals can also survive and have offsprings that could potentially inherit these weaknesses, and as this continues it could perhaps leave nearly all people suffering from such conditions further into future.
Does that sound like a realistic scenario? (Assuming we don’t destroy ourselves along with the environment first…)
There’s barely any pressure to extinguish “bad” traits, though.
If you’re the idiot who eats every berry you can find, cavemen can’t save you and your genes disappear. Modern medicine can and will save you, so you can create offspring and the berryeaters keep their proud heritage alive.
Now, what is considered “good” or “bad” is of course highly debatable, but currently we have effectively no survival pressure, the only selection is how many children you get.
But that if that “idiot” does propagate, but so does everyone else, no skin off the species back. If the selective pressure returns, well then the others keep going.