It's unfair to say this is due to senior engineers refusing to push boundaries. A team (eng + product + management) collectively defines its vision and strategi

It's unfair to say this is due to senior engineers refusing to push boundaries. A team (eng + product + management) collectively defines its vision and strategies. I'm on my 3rd team, and 2nd PA in 9 years at Google and I've never seen a dearth of upward mobility opportunity for any junior engineer who wants it. There are almost always new an innovative projects beginning and available to work on.