There are countries that had 5-10% or more or their population being new immigrants in the span of a few decades.

For a country like the US, with no ethnic cohesion, and even less cohesive culture, where everybody is an immigrant of at best 10 generations anyway, this might not be a problem.

For other countries this can have a significant impact in everyday life -- especially when it's not Indians IT scientists with H1B visas coming in, but immigrants lacking skills or coming from widely different cultures.