To answer directly

Asmongold is a guy that likes to do whatever he wants, but when he played XIV everything was XIV
Entering his comments? XIV
His Subreddit? Only XIV memes and stuff
When he wasn't playing? "Hey XIV when"

Think that was the main reason, XIV community can be as annoying as it can be, specially with MSQ, when people wait for a streamer to react to "that one scene" they're already overhyping the next one, and the next one, and so on
I don't really blame him for not wanting to continue despite being an overall good product
+ as an extra i think he complained about the amount of text?
Wich perse is not a problem but for a streamer having to read so much text was bothersome for him or some thing like that