It really seems like they lost the few key people that were holding the whole thing together, either to another company or just to the void due to bad management.

I would love to understand more about this change.

The more I mature as an engineer, the more I see the value of few engaged Individual Contributors that behind the scenes are driving the product and steering management decisions.

It is often under-appreciated how much an active corporate engagement model is due to 1 or 2 highly motivated employees. Once they leave, engagement drops because it wasn't something being driven from management or PMs.