It's really more of a case of the communities growing despite the quality of their games tbqh.
CS:GO got very little support apart from the occasional patch or update. It only really became the monster it is today when Valve figured they could monetize in every aspect of the game (skins, operations, etc). Before that happened it was the fans that kept it going with custom games, maps, etc. Valve recently even went out of their way to shut down some of these community managed servers.
Dota experienced similar issues. It got more attention than CS:GO did because it was a newer game, but it's impossible to forget the clusterfuck that Reborn launch was, the loss of features and the sheer amount of bugs we got. It's also impossible to look away at the fact they are slow feeding us content that should have been in the game years ago, we still don't have hero parity with dota 1 for instance, while constantly pushing out more hats and compendiums.
At the end of the day it was a very poor showing from both parties and I honestly think Valve should have shown more respect towards someone that helped their game be what it is today. It's undeniable the good that his work during TI2 and TI3, mainly, did for the game, especially if you consider that at that time it was nearing the end of the Beta stage.
Also, after reading James essay, it looks like one of the main issues between Valve and him was that Valve was trying to sell this game as a sport, surely to increase even further the target audience and maximize the hat sales. E-sports are not sports and will never be, and that's a good thing.
