Actually, they thought they did understand “junk” DNA. They figured that evolution is an untidy, trial and error process that generates lots of functionless DNA that accumulates in the genome like junk. In short, it was a prediction of neo-Darwinian evolution that was applied to non-coding DNA, only to find out after decades of assuming that it was functionless “junk” that the non-coding regions are probably even more functional than the genetic DNA!
Spoken like someone who has all the "experience" of reading "science" writers like Brian Thomas MS*
Very plainly, you don't know WTF you're talking about and making it up as you go to your flock in your echo chamber is what you're limited to.
Junk DNA was labelled as junk DNA very simply because it had no known direct function. Not that it had no function.....that it had no KNOWN function....and ever since it was dubbed "junk DNA" in the early 70s.....ever since it was shown that there was DNA with no KNOWN function, that there was non-coding DNA....REAL scientists have been trying to find its function while your "science" writers have been "writing"...