I think the good will that Blizzard earned with their early games has been eroding for a long time. They did, legitimately, used to have enormous community good will. I can think of two ways that's eroded:
(1) Blizzard's early games earned huge amounts of goodwill by enabling players to mod them. The map editor of Warcraft and the UI mod-ability of WoW let people build entire communities around modded content (DotA, for example!). To my knowledge games after Starcraft II have largely lacked anything resembling this kind of functionality (please correct me if I'm wrong). Hearthstone, HotS, Diablo 3, and Overwatch all have 100% of their content locked down from the top down. I don't think the contribution of mods to the longevity of Blizzard's early titles can be overstated, and I'm confused why they haven't kept up that spirit.
(2) Blizzard has had a long string of eyebrow-raising failures to foster the competitive gaming scene, which they've been tone-deaf on since at least Starcraft II. They pulled the cord entirely on HotS after getting the game into great shape, the kept the Overwatch meta unbelievably stale for years, the Hearthstone Grandmaster League has been a joke on multiple fronts (in addition to an objectively stupid format decision for the first season, they insist on reserving seats in their flagship tournament for popular streamers rather than top players, resulting in some just... awful games). In general they try to retain far too much control and stifle anything they feel inconveniences them.
Add to that (3) a string of jaw-droppingly bad community management moves ("you think you want that"... Diablo for mobile...) and (4) Activision looming like an insect and (5) lots of Bizarre changes to games to appease Blizzard China
I don't know, I used to perceive Blizzard as a good steward for games. Now I don't think the game makers have that degree of control over the company's decisions, or their priorities have changed.
So it doesn't surprise me that people were as quick to kick them to the curb as they were. It would have 10 years ago, but not today.