Nationality and Country of birth, are two different things.
If Elon Musk was born in India or China, and when he was 1 yr old he moved back to South Africa, and rest of his life remained unchanged from what has been, then he'd not be granted a permanent residency as easily and may have just become a US Citizen in the last two years. Can you imagine what loss it would be to the US if Musk had to wait so long to become a US Citizen?
Likewise, if a China-born French citizen were to apply for employment based permanent residency in the US, the green card backlogs would be too onerous for one to succeed as an entrepreneur.
Also, place of birth limits currently is used purely for limiting the number of immigrants born in a country gaining Permanent Residency in the US. So, a person born in a country like India (world largest democracy, with freedom of religion, minority and women's rights and equality in races etc) has to be in a much longer queue to get Permanent Residency than a person who is born in say Sudan or Iran or Pakistan or any of the other Islamic nations where there's no legit democracy or freedom of religion or minority rights.
Hope this helps in understanding the earlier comment in context.