Maybe because Bezos stops being involved and there is nobody inside the company who dares to change whatever Bezos has implemented?

Reading the tweets, it seems like Bezos made all the important decisions. If he is not around because he is focussed on other projects, who could do it instead? Judging by the story that Bezos didn't allow any pixel to be changed on the Amazon homepage, I can imagine that this is a pattern and whoever tried to implement a change doesn't dare to try it again.