So it's not really any different, besides of course that transcribing someone's licks and incorporating it into your own style isn't going to get exposed.
What do you mean "isn't going to get exposed" , people complain all the time that certain songs re-use riffs from older songs.
Your argument seems to boil down to what the minimum unit of valid IP is. This is a complex issue and is often fought in courts.
Taking a riff from someone elses song and rebuilding a new song around it requires a lot more creativity time and money than simply copying and redistributing the song.
Copyright isn't so much for protecting an "idea" as such (that's what patents are for).
It is to stop somebody reproducing a complete piece of work without prior agreement.
Let's say I build a new type of software and publish it, then somebody else thinks that is a good idea and builds their own version that is similar to mine (without re-using my source code). I would view that as flattery and competition. However I have a strong first mover advantage and whilst they may have learned from some of my mistakes they still have to actually do the work of creating their software which puts us economically on a relatively even footing.
Suppose instead they simply redistribute my software with their logo on it for half the price then they have a strong economical advantage because they didn't have to invest the initial development costs that I did.
So it's not really any different, besides of course that transcribing someone's licks and incorporating it into your own style isn't going to get exposed.