Googler here.

In general, yes we do practice it. They are guidelines, not rules tho.

Is Angular grossly over-engineered? Depends on how you look at it.

Any code's complexity reflects the complexity of its use case and Angular, for example, needs to fit A LOT of use cases at Google. So yea, sometimes, I think it can be a big hammer for a small nail. In other cases, all that abstraction helps. I guess that's the nature of how code eventually matures over time.