> Don't these kinds of frankenstein mashups of different malware components of various quality occur pretty often

Yes.

> Or are all the components previously unseen?

Not really.

From TFA:

"My current gut feeling about all of this is that someone basically was designing a piece of Mac malware that would give them the ability to completely remotely control an infected system. And then they also added some ransomware capability as a way to make extra money."

That basically described how ransomware was born, god knows how long ago.

IMO the better question is why the hell attackers targeting macOS haven't been doing this until now (if we take their word for it).

> is there some reason the interviewees and reporter imply this is a mystery?

I suspect the reason is boring: they want to grab eyeballs.