Chain migration is real and over 1 million people a year are migrating to the US. The genesis of this was from a change in a single law back in 1965 that eliminated a cap on how many could be legitimately sponsored for Green Cards. Once you have a card, you are quickly able to apply for citizenship, which also had no limits.
https://www.fairus.org/issue/legal-immigration/chain-migration
As that post states, we have had no merit requirements, like Canada and other countries have. I have a friend that was a pharmacist in his country and had a just gotten a Masters degree from a top US university who was helped with two years on a USAID scholarship and Canada was only considering him and not his wife or kids! Canada (and many other countries) has greatly disallowed chain migration.
The problem with immigration from south of our border is that they generally come illegally.
Of course, H-1B visas and the like have not been properly policed to meet the actual original intent.
Interestingly, none of this is the fault of the immigrants who come here legally. They are merely following our laws and doing what is best for them and their families.
The fault is with our own laws or the enforcement of our laws.
Welfare access is not supposed to be allowed. I have an extended family member from another country and the USCIS mandated the family had to show it could handle all financial needs, as welfare of any sort was not allowed. Unfortunately, there are plenty of opportunities to evade that and even illegal immigrants get welfare. The extended family never used welfare, but then they also had no other country to flee to if they did something that could be found to be illegal. All other immigrants typically do.
Immigrants rarely give up their prior citizenship—including my extended family member. Typically, it is due to preferential treatment they can have as they deal with their aging parents. I do believe that dual citizenship leaves people with dual allegiances by definition. This, along with other considerations, further restricts the speed of assimilation into the US to where the immigrant now has more understanding of the responsibility of the tax and social concerns and can help the US via voting for healthy changes.
My friends are from Gujarat, where I believe that PM Modi hails from.
Regarding the ROP, I have seen and encountered outright fraud only to experience city officials not seem to care at all ...
Not true with Indian immigrants who have to give up their Indian citizenship if they wish to take another. India does not allow dual citizenship for the very reason you mentioned. A point specifically regarding Indians taking advantage of welfare (I understand that you made a very general point, not necessarily directed at Indians), it may happen but it is pretty uncommon.This is the ethnic group that has the highest median income of any in the U.S.
https://en.wikipedia.org/wiki/List_of_ethnic_groups_in_the_United_States_by_household_income