Discussion of the use of circuit breakers in audio components can be found in the following threads. The bottom line would seem to be that it may be suitable and beneficial to use some breakers in some applications but not in others, with breaking time being one of several significant considerations:
https://forum.audiogon.com/discussions/anyone-replaced-fuse-with-circuit-breaker
https://forum.audiogon.com/discussions/by-pass-fuse-and-add-a-circuit-breakerAlso, use of a circuit breaker in a DC rail application may be problematical in many cases in terms of where it is located and how it is wired to, with the possibility of noise coupling to or from that wiring having to be addressed.
Finally, I would imagine that in many cases a factor is that designers tend to go with approaches they have used previously, and are familiar with, and do not require significant time for evaluation and experimentation in return for sonic benefits that may or may not occur.
Regards,
-- Al