I agree with you on most points. I would like to supply a different analogy for immigration and absorption from the physical sciences.
Immigration at a certain level, with assimilation of most of the immigrants, is a good thing—it supplies what in the agricultural world might be called hybrid rigor, and definitely adds to our cuisine. The question is how to think of the level above which assimilation becomes less thorough, or indeed impossible.
In materials, you can melt dissimilar metals and mix them together in a pot. Depending on the first metal, and the metals that are introduced, you may form an alloy. Think of tin and lead mixed together as solder. Before our current lead worries, this mixture was used by plumbers and electrical manufacturers was 60/40, close enough to the 63/37 ratio that produces the lowest melting point.
Other metal combinations can’t mix as well. Put in too much, and instead of an alloy, you’ll get lumps of the additive in a matrix of the main metal.
The same thing happens with liquids. You can only dissolve so much salt in water before additional amounts sit on the bottom.
So it is with immigration. There is a maximum rate of absorption for incoming immigrants without disruption. Further, experience shows the annual number of immigrants that can be imported without major problems varies with where they come from. Liberals are willfully blind to this, alas.
Very true, and I think it's because the culture they come from has similar moral boundaries.