So here's a weird question: Supposing companies multi-home for DNS, or whatever other essential service, via multiple service providers.

Whatever multi-home means, why can't there just be one service provider that does that? And are we sure that these service providers aren't already doing that as best we might hope for? (For instance, Amazon already has multiple zones, etc.)

I suppose the one thing this can't protect against is some sort of political (broadly defined) threat related to the company itself.