Jeri couldn't get buy-in for her projects at Valve so they failed. For a project at Valve to succeed you need to convince a number of other people at the company that your project is a good idea and that they should help you work on it. It sounds like she wasn't able to convince others at the company to come help her on her ideas (maybe because she didn't put forth the effort, she wasn't good at selling it, or no one thought her ideas were worth it).
Valve has a very specific culture and you have to really have a certain personality to fit in. Sounds like maybe she wasn't a good fit.
[1] http://hardware.slashdot.org/story/13/07/09/0214225/former-v...