Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
That makes no sense. It’s easy to have multiple cultures with cultures that don’t assimilate. In fact, not assimilating is required to end up with multiculturalism, otherwise everyone ends up assimilated in to a monoculture.
Though perhaps it’s just stemming from the use of “accept” instead of “tolerate”. Those are two very, VERY different words.