Blizzard’s main cash cow by a very large margin has always been WoW. They started developing another MMO (codename Titan) which they ended up scrapping and turning into Overwatch. Overwatch was their golden baby that they hoped could be in the same league as WoW.
Turns out, it wasn’t. Esports flopped despite huge investments, and the whole company went through a lot, including being sold now, which saw all of their games including WoW and OW go through monetization overhauls, and voila a FTP OW.