Earlier quoted context omitted.
Its not an act of omission, this is a result of compromise with factions that don’t want immigration at all. The fact it discourages people is a feature not a bug.
If you immigrate, you emigrate. If you successfully immigrate (let's say in the U.S.), you have skills sought there. Those skills are probably also in demand in your origin country. You'd stand even more of a chance to be one of a few in your home country, gaining status, gaining visibility, turning the tide. I know I'll probably be flagged for this question, but still: why do this? Why not help your origin country w…
That's not guaranteed to be true. Take finance - if you want a career in this field there's only a handful of cities where it makes sense to live and work: London, Singapore, New York, maybe Tokyo.
An exotic derivatives quant won't find much demand for their skills in, say, Almaty.
Similarly, tech workers benefit from being in tech hubs (SV being one example). Oil engineers need to be around oil rigs and so on.
Moreover, standards of living are different in different parts of the world. Levels of corruption, infrastructure development, civic engagement etc are much worse in some places than others. You may have had the foresight of choosing to be born in a well developed country, but many have not.