It's the most effective strategy because it incurs the least cost for the most effect. It deals with it quite nicely, and there is very little social disturbance.

Whether I think it's a bad thing, or need a strategy, is irrelevant. Japan has implemented such a strategy. I can't speak for Finland's current state because I'm very misinformed on that country, I've learned recently.

Indeed, you won't come up with and implement such a strategy if you think the costs of cultural diversity will be greater than the opportunity costs of not having any + costs of preventing it. This doesn't prevent anyone from noticing, naming, and perhaps even analyzing this strategy once it has already been used and shown to the world, even if we disagree with the reasons behind its implementation (or disagree on the specific meaning of "dealing with" - for them, not having any is just as much "dealt with" as for us a long-term, self-sustaining/reinforcing, mutually-beneficial ecosystem would be "dealing with" multiple cultures).