Take a Bach Fugue, where the notes and harmonies are very important, and 'complex' with lots of rules, patterns, intertwining melodies. The specific instruments used doesn't always matter, most pieces could interchangeably be played on piano or harpsichord or organ and sound as beautiful.
Then let's look at something like Scary Monsters by Skrillex, where the entire drop is pretty much just a G with a small melody coming in every 4 measures. There's not much melodic complexity going on there. But the sound production, synthesis and processing is insane. After that song came out everyone was trying to figure out how to make a talking bass that sounded like that. And even years later, barely anyone has figured it out, I've only heard really famous synthesists like Rob Swire get a close sound.
Is a Skrillex drop as complex as a Bach Fugue? If you're just comparing the arrangement, or the melodies, not at all. But the Skrillex song isn't about the melody as much as the texture and dynamics. Bach didn't specify precisely what harmonics should exist in the instruments playing his music. Skrillex probably could not write a Fugue to the standards of Bach's best. But I bet if you sat Bach down in front of a laptop with an FM synthesizer, he couldn't create a "sick drop" either.
It gets entirely too subjective at this point. A lot of people will disagree with me that the production and synthesis techniques should be considered part of music theory or composition. But I think they're concepts that you couldn't replicate certain music without. In my opinion the palindromic structure of a Boards of Canada album is on par with something like Bach's Crab Canon. They just get there in totally different ways.