Back in the 80’s, a friend noticed the isomorphism between punk rock and rap. Stripped-down, edgy, violently angry, atonal, lots of yelling. Music for angry young men.
I was very late in discovering both the highly-technical grindcore/death metal styles, and highly-technical IDM like Venetian Snares. I’m noticing now how similar they are/were. Very complex, almost (or in the case of IDM, definitely) impossible rhythms, lots of atonality, and harsh, violent anger. Music that really challenges– almost flips off– the audience. Brashly, unapologetically, and defiantly intellectual, with a “statistical density” (Zappa, the first IDM’er!?) that says, “Just you try and figure this shit out!”. And they both came into popularity at the same time, the mid-to-late 2000’s.
What I found interesting about the rap/punk isomorphism in the 80’s is that one evolved out of the dance/disco scene, the other out of the rock scene, and fairly independently, since the two scenes were fairly antagonistic (and, at the time, racially-divided too). A similar kind of parallel evolution seems to have happened with grindcore and IDM: one emergedout of the dance/disco scene, the other out of the rock/metal scene, and not too much overlap between those two scenes.
Of course, the trends have moved on, and I see parallel evolutions happening in the realm of ambient-noise and metal-noise: noisy non-rhythmic clouds of sound, converging on white noise, but one coming from a group making the noise via computers, and the other from a group making them via guitars.