Any criticism I've read seems to be based around how she's a woman and she used her womanness to get ahead.
Nothing she has done as the CEO of Reddit is evidence of the need for the awful insults and copypasta I've seen lobbed at her. And these aren't hidden in the recesses of MRA subreddits, they're the top comments on any thread with any mention of Pao.
It's like being a software engineer and getting a new manager that previously worked at Goldman Sachs, wears expensive suits to the office, asks you for help using Microsoft Word, but then tells you to switch from IntelliJ to Borland JBuilder because he owns some shares in Borland. He doesn't get the culture, he's an outside and is making decisions to actively ruin your environment. That's how it feels.