> Or am I misreading that.

Yes:

    developer.apple.com. 73 IN CNAME developer-cdn.apple.com.akadns.net.
    developer-cdn.apple.com.akadns.net. 73 IN CNAME world-gen.g.aaplimg.com.
    world-gen.g.aaplimg.com. 13 IN CNAME apple-c.g.aaplimg.com.
    apple-c.g.aaplimg.com. 8 IN CNAME apple-cf.g.aaplimg.com.
    apple-cf.g.aaplimg.com. 8 IN CNAME apple-lr.g.aaplimg.com.
    apple-lr.g.aaplimg.com. 14400 IN NS b.gslb.aaplimg.com.
    apple-lr.g.aaplimg.com. 14400 IN NS a.gslb.aaplimg.com.

The Akamai CNAME just points to a series of aaplimg.com CNAME (eventually ending up with apple-lr.g.aaplimg.com), which is Apple's own CDN domain. The CDN's resolvers (a.gslb.aaplimg.com and b.gslb.aaplimg.com) refused to serve A records for apple-lr.g.aaplimg.com.

They fixed that and now it's back up.

This kind of setup is typically done for flexibility reasons (geographical DNS load balancing or similar, where the Akamai DNS servers serve as the geo LB).

> It's generally considered bad form to have the all the DNS servers for "example.com" under "example.com", by the way. If you mess up "example.com", or it goes down, getting to it to fix it can be difficult.

Not necessarily - this is what glue records[1] are for. Many large companies host their authoritative DNS on the same domain, it's not a bad practice when done carefully.

[1]: https://ns1.com/blog/glue-records-and-dedicated-dns