Comparing blizzard to paradox is kind of pointless.. But yes, blizzard treated their playerbase very badly. Not only Sc2 but also Diablo3(that entire development was surrounding with devs stating 'we know better'), WoW and probably other game playerbases got treated badly... And they are paying for it... From being beloved company by entire generation they became a laughing joke put on par with companies like EA. And loosing player base trust might result in huge repercussions(if not now then in the future.).
Its not just the whole "treating the fanbase poorly thing" - all though that's reflective of the problem.
The bigger problem is that their only truly fresh IP in 20 years is Overwatch.
There's also the split fanbase. Pretty much everyone who plays Paradox games wants varying levels of depth...Stellaris is the simplist Paradox game and its absolutely mind-bogglingly complex compared to most games. Half of Blizzard's fanbase wants games that are as deep and complex as EU4 while the other half seems to want World of Warcraft: Candy Crush Edition.