They use Discord for illegal stuff because they already use it for tons of other things. Sure it's a bad idea, but they don't care (and with all honesty, Discord support doesn't seem to either).
Synonyms for discord
conflict, disaccord, discordance, discordancy, disharmony, dissension (also dissention), dissent, dissidence, dissonance, disunion, disunity, division, friction, infighting, inharmony, schism, strife, variance, war, warfare
Seems pretty fitting? :)