These companies are organizations who can change rapidly as management and staff turn over. Blizzard from last year isn’t the same as blizzard from 5 years ago isn’t the same as blizzard from 20 years ago.
The veneration of brands based on their inheritance from what the brand used to be distorts people’s view of reality, and leads to brands that feel they don’t have to continue in terms of excellence.
Personally I think the start of WoW was the end of an age for Blizzard. Similarly the release of Fallout Shelter was the end of an age for Bethesda. Beyond those points the organizations were distorted by the success and profit they encountered there, and basically shifted to new companies with different priorities yet still holding the brand name.