I suppose the purists use tape and razor blades, like their heroes of yesteryear. Like I used to do myself.
Before discovering MIDI sequencers (Cakewalk 1.0, c. 1988), the simplest arrangements would take me days to assemble. Keep in mind that a 3-note chord requires 3 separate tracks with a monophonic synthesizer, and I only had a 4-track machine. There was always a sense of accomplishment at the end of the process, regardless how mundane the composition.
This is a big part of what makes Tomita's Snowflakes are Dancing such a monumental feat. It took him 2 years and lots of splicing and bouncing. And he didn't have a technical guy on hand like Carlos did; Tomita's was the only synthesizer in all of Japan at the time, and he the only (self-taught) expert.