It's not good as a first line of defense for failover, but with some client software and/or failure mechanisms there aren't any better approachs I'm aware of. Some of the software I administer doesn't understand multiple A/AAAA records.

And a BGP failure is a good example too. It doesn't matter how resilient the failover mechanisms for one IP are if the routing tables are wrong.

Agreed about some providers enforcing a larger one, though. DNS propagation is wildly inconsistent.