Blizzard found some of the founders/high accounts were doing RMT (which is the bannable part. Actually just selling runs for gold is 100% legal within the confines of the game). They were also sharing many, many 'banking' accounts, which is also very 'illegal' according to the TOS.
The bank accounts being banned means that BILLIONS of gold just evaporated from the world, so rather than deal with the fallout of the bans, they (Gallywix founders/managers) just deleted everything. Twitter, Discord, websites, etc. All gone. Anyone 'owed' money by them will never see a copper.
They also did Hardware ID bans, so they not only killed their main accounts, but all of their alt accounts, family members who play on the same machine, etc.