So this begs the question, what are the problems CCC and MA each create?
The main reason I like cloned drives is because I like to have a spare drive(s) that I can use to boot up in for trouble shooting, or for accessing old software that I can no longer use. The Disk Utility GUI on older MacOS comes to mind, having more options such as creating software RAIDs.
One other issue with Migration Assistant is the time it takes. Every time I use the MA, it seems to take a very long time, much longer than cloning a drive.
Also, I have had MA fail on me before.
IIRC, after using MA, there is still things that have to be set up, loaded, signed in, such as Photos app. A cloned drive it ready to be used, with maybe the exception of Keychain and maybe iCloud if the cloned drive is used on a different computer than the source drive.
One thing that MA has over cloning is if there is corrupt data on the source drive, then it would be more likely to see it on a cloned drive versus a MA set up.
One issue I am not sure about, maybe one of the more knowledgeable people on here can answer this, is whether all system files, such as drives, are on each OS install. Meaning, if I clone my Mac Mini drive, and try to use it on my Mac Pro, does the Mac Mini system folder contain all the files needed to use the Mac Pro's HW, like GPU for example.
One mroe thing about cloning, I noticed when using a cloned drive from a 2011 MBP on a mid-2011 iMac, the iMac is labeled as a MBP. I am not sure if this is a problem other than the name being off, the iMac runs great otherwise.