Try explaining to your local regulators why your bitcoin balance has traces of illegal/laundered money in it...because a drug overlord's purchase was destroyed and the funds were gifted to the community.
Also, I imagine you'd explain it to regulators with "a drug overlord's purchase was destroyed and the funds were gifted to the community". They're not stupid - if I obtained a "tainted" bitcoin and emailed fractions of it to everyone I didn't like, I doubt the authorities would be naive enough to put all my enemies in jail.