I read it a couple of times and the sense I get is that “de novo” actually means “ex aliquid”, from something. Just because they call something a junk gene does not mean it is a junk gene. Lots of things the scientists originally thought were evolutionary dead ends or leftovers were actually doing something quite important, i.e. the appendix. There are other studies showing those genes do have a purpose, and if “evolution” or “natural selection” changed them, the organism would not be able to function.
Bingo!
It may be junk to you and me, but the hoarder keeps it around and will occasionally go through a room of stuff looking for something that fits a need.
There’s a thought, every cell in our bodies, indeed every cell on earth, is a hoarder.
Small wonder I can’t clean the garage...
Just because they call something a junk gene