I actually don't get much of the Marissa-hate around here. I've worked with her - she was the executive sponsor of a couple projects I worked on when I first got to Google. She has her flaws, but in general she's both smart and very hardworking. CEO of Yahoo is a tough job for anyone - as evidenced by the 5 (!) CEOs in the 5 years before her - but the real mistakes made in Yahoo's history were made in the late 90s and early 2000s.

It's pretty likely Twitter will follow the same path, but the real mistakes made in Twitter's lifetime were made between 2010-2016.