Yeap, that's specifically what I also implicitly meant by "Spread your name servers" (besides having them distributed). To use this technique, you also must have a "Business" account with Cloudflare ($200/mo), so to leverage their ability to front your websites using CNAMEs : )
This got me Googling, and best as I can tell, CF doesn't support zone transfers. (They support being a client, but not a server. So, they could function as one's secondary system, but not as the primary.)
I imagine/hope a lot of the heavily engineered ops teams don’t use zone transfers, instead using APIs. The idea of primary and secondary wouldn’t really a strong indicator at that scale.
Sure, I could use the CF APIs… but to do what? AFAICT with a quick look over the documentation, there isn't any way to tail a log of changes being made to the zone. (You can export the entire thing in BIND format, though, the example in the docs has several errors in it that make me wonder how well that would work.) (The idea with zone xfers is that it is at least semi-standardized, whereas CF's API, while useful, is not.)
Then I'm stuck with a bunch of bad questions about how often to poll, and whether CF's rate limits would support any reasonably quick poll interval.
(The big problem is that we have other tooling that relies on being able to update DNS, the big one being ACME for certificate renewal. The changes it makes to CF would need to be rapidly replicated out to the nameserver.)
(Nothing in the post really strikes me as particular to CF, either. I think I could easily replace everything I've said here with "Route 53" and end up in the same bucket, maybe plus or minus zone xfers working.)
