He still killed plenty of people, innocent as much as guilty and what Discord did was bound by HIS nature as being chaotic.
Zuko sided with his evil sister and father, got Aang nearly killed, sent a hit man after him to finish the job, sent his uncle to prison. Vegeta killed a village of namakens, let Cell reach his perfect form that almost destroyed theeearth and happily let himself be taken over by Babdi so he could be strong enough to fight Goku when they should have been focussed on stopping Majin Buu. Neither of them are perfect but timeproved that there was more to them.