First, dreamers did not do anything illegal. Their parents did.Millions of people who, rather than following our laws for legal immigration, purposefully seek to invade our country illegally are by definition, not assimilating. This is not complicated.
I don't agree with your definition of assimilation into the USA. I see it as becoming a functioning member of society w/o causing harm regardless of legal status other than having a deportation order hanging over your head. You apparently think it means first being legal.