Saying quality is different than qualities plural. It's the kind of language used by rationalist[1] or HBD/eugenics adjacent movements that believe each person's value to society can be reduced to a single number. Too close to fascism for comfort.
That's obviously not the case in this context but it can get confusing so you should just avoid it. There are legit reasons to be suspicious of anyone talking like that. It's better to say "expected economic value" or "readiness to integrate" when talking about immigrants so you don't get mistaken for a racist.
No one in this discussion except you expressed the idea that quality of a human can be expressed by a single number.
A more natural concept of overall human quality would be something like a linear combination of individual qualities in a multidimensional space.
a. Smart person - good, positive coefficient.
b. Diligent person - good, positive coefficient.
c. But works for the mob as a money launderer - bad, very high negative coefficient, probably high enough to drag the overall combination under the neutral hyperplane, so to say.
Sure, but it doesn't work like that in public discourse and it's hard to believe that you are oblivious to that.
That 19 year old dark skinned refugee from Syria who has just arrived in Poland in 2015, doesn't speak the language, is physically fit, basic school education, quite some trauma to process though. That's what the far right racist nationlists there would have called a low quality human. Don't use their language if you don't want to be associated with their views.
And indeed, if their trauma is not processed and they are left in a ghetto with other traumatized folks, that's a recipe for violence to eventually erupt. But if they get help by a psychologiest and a chance to integrate, they can contribute to society immensely, build a life, become the best neighbors you could wish for.
Now, what is the "quality" of such a person? Or maybe rather: What is the quality of how we treat them.
Regular economic immigration processes, which is what is mainly being discussed here, are usually centered around measurable skills and other traits such as criminal record.
BTW you don't know many Syrians if you consider them dark skinned. They are classical Mediterranean people, the whitest of all Arabic-speaking nations. You won't be able to tell a random Syrian from a random Greek.
That's obviously not the case in this context but it can get confusing so you should just avoid it. There are legit reasons to be suspicious of anyone talking like that. It's better to say "expected economic value" or "readiness to integrate" when talking about immigrants so you don't get mistaken for a racist.
[1] Used here as a slur.