In practice nonce reuse with CTR+GCM virtually always results in an obvious exploitable vulnerability. With CBC+HMAC nonce reuse sometimes results in an obvious exploitable vulnerability but often results in a system which has unclear security properties but which isn't known to be practically exploitable under common use (and may even still be provably secure under after careful analysis).
In other words, if the latter system is flawed it ends up having the sort of security properties more akin to physical security rather than the strong mathematical assurances we expect from cryptographic systems.
Given the high rate of issues with nonce mishandling in real systems, even ones that appeared to be carefully engineered, it shouldn't be hard to understand why systems engineers (as opposed to, say, cryptographic researchers) would have an unambiguous preference for one over another when it comes to practical systems, at least if all else were equal (which, of course, it seldom is!).
> IMO those assumptions are not a good foundation for security and we should move past them.
No one here is advocating that using CBC with intentional potential IV reuse is good security. But defense in depth is a good security practice and using primitives that fail less catastrophically when inevitable disasters happen is also a good security practice.
This is doubly so because there we know that that some sophisticated attackers have been known to exploit the brittleness of otherwise secure schemes to compromise implementations. Brittleness doesn't just increase exposure to chance it also makes it easier to inject bugdoors and to plausibly deny them.