Google is Losing Top Talent; Twitter is Growing It
mashable.com
mashable.com
I also suspect that the challenges Twitter faces are more business-oriented - they probably attract a different type of talent.
TL;DR Google is frickin' huge and just plain different than Twitter. It makes no sense to compare the two this way.
Yes, that's horrible. It's harder to get a decent transfer than a promotion, but if you start out on a dud, you're not going to get either on a decent schedule.
Did they say why they were keeping you stuck there? Don't they realize that they're losing good people with these policies?
For most people (the 80% that will never get anything interesting, but that Google will happily use for grunt work) Google is culturally a halfway house for those who are afraid of adult life. You have foosball tables but no chance of getting on a good project. It's infantilizing.