I agree with part of what you said, although I'm not sure the "self segregation" of ethnic groups is really a major explanation of the problem?
If you actually come to America with the intention of working at a career type job, you're probably getting hired into an environment where you can't segregate yourself. You might choose to live around only other immigrants of your same nationality, but the workplace is going to be a mish-mash of people who are forced to spend at least 8 hours a day together, under the same roof.
It's always been the case that most of the time, people prefer to reside around others who are more like themselves than different. I grew up in St. Louis, Missouri -- and to this day, it still has an Italian neighborhood, and a German neighborhood, and even a small area one could call a "Chinatown" (though the Asian population there isn't big enough to sustain the kind of Chinatown districts you see in places like New York, DC or Chicago). Those are holdouts from immigration that happened long ago.
Where it becomes a problem is when groups come here with the wrong motivation. If you're coming to America because you really view it as the "land of opportunity", where you can find a good paying job doing something you enjoy doing? You should do well here and be welcome here, even if you try to live in a community full of others from your home country. Others come here with intentions of slowly taking over America -- forcing cities and towns to "do things their way" as they get enough of their own people to move there. (Hint: If it's a big deal for you to keep flying the flag of your home country after you immigrate here? You *may* not be here for the right reasons. Why aren't you back home, contributing to make your home country a better place, if you're so proud of it?)
If you actually come to America with the intention of working at a career type job, you're probably getting hired into an environment where you can't segregate yourself. You might choose to live around only other immigrants of your same nationality, but the workplace is going to be a mish-mash of people who are forced to spend at least 8 hours a day together, under the same roof.
It's always been the case that most of the time, people prefer to reside around others who are more like themselves than different. I grew up in St. Louis, Missouri -- and to this day, it still has an Italian neighborhood, and a German neighborhood, and even a small area one could call a "Chinatown" (though the Asian population there isn't big enough to sustain the kind of Chinatown districts you see in places like New York, DC or Chicago). Those are holdouts from immigration that happened long ago.
Where it becomes a problem is when groups come here with the wrong motivation. If you're coming to America because you really view it as the "land of opportunity", where you can find a good paying job doing something you enjoy doing? You should do well here and be welcome here, even if you try to live in a community full of others from your home country. Others come here with intentions of slowly taking over America -- forcing cities and towns to "do things their way" as they get enough of their own people to move there. (Hint: If it's a big deal for you to keep flying the flag of your home country after you immigrate here? You *may* not be here for the right reasons. Why aren't you back home, contributing to make your home country a better place, if you're so proud of it?)
Immigrants don’t make our country stronger because we live in the age of identity politics. Ethnic groups self segregate. There is no longer any force compelling them to integrate. So we end up with groups who aren’t a real part of the whole and who in fact express great animosity to their hosts. That is a real big negative.