While a group can "tank" outsiders shitting things up to a degree, the ratio of outsiders vs insiders is always extremely asymmetric, and the outsiders are not just random, they are often organized groups themselves who prey on other group's kindness.

America does this with being a citizen or not, barriers to citizenship, etc... but while that was good enough as a growing country in the context of migration, now as a large stablished population it doesn't work as well as it should.

This is why I believe in stratocracy that expands the citizenship barriers and conditions freedom (and enables even more freedom) to commitment.