If the content that Zach posts was through a PR person, people would grouse about the content of the posts, but wouldn't normally attack the PR person, because, generally, you don't shoot the messenger.
But since Zach is Imagineering, he becomes the lightning rod for the content and people seem more than happy to shoot the messenger because he's also the origin.
Add to that that Zach can be quite hyberpolic in pre-emptively defending and promoting what he and the other imagineers are doing. And nothing sets people off like hating something and someone pixie-dusting over it.
Because of this, some hate everything Zach says and does, even if it's stuff they don't particularly dislike. Then they go out of their way to insult Zach whenever possible, even in very childish ways to score their hate-points. It's Zach Riddley derangement syndrome.
I'm not saying he's above criticism in the way he interacts with the public, nor am I saying that his work is above criticism. Just that some elevate their dislike of him to 11 in all things, which isn't helpful.