I had a driver in a Ford F-150 do this in front of me last week as he pulled away from a light. The smoke totally blacked out the windshield for 5 seconds while I was in motion. I was totally blinded by this.
I had no idea this was a thing, much less that it was something people did on purpose.
I wish they'd go back to just hanging plastic testicles from the trailer hitch, honestly.
It's very much on purpose. To do it with a modern diesel truck you need to remove the DPF, and reprogram the ECU to run rich and to ignore the missing DPF.