Here's a link for further info. Accordingly to the previous CEO (Yishan Wong), u/kn0thing forced Pao to fire the communication director Victoria Taylor, also known as the person who organised the AMAs (a big deal for Reddit back then, and largely responsible for its popularity). u/kn0thing eventually admitted to be responsible for firing Taylor, but Pao was the one that took the userbase's backslash.

And while this is conjecture, I'm led to believe that she was also a scapegoat on creating the precedent for banning subreddits. The userbase hated her, as that was seen as "going too far", and yet this would become necessary as the site grew (and the subreddits in question were harassing people IRL). Then the following CEO (Huffman) would use and abuse subreddit bans, but since the precedent was already there, users didn't blame him for that.