If I had to summarize the change, I'd say that it's evolved from an expertise-based system to a data based system. The reason why eight people were present at every planning meeting is because their expert opinion was the primary tool used in decision making. In addition to poor decisions, this had two very negative outcomes:
1) reputation was fiercely fought for. Individuals feared that if they were ever incorrect, the damage to their reputation would limit their ability to impact future decisions and eventually lead to career death. Whether this actually happened or not is irrelevant; the fear itself caused overt caution and consensus seeking.
2) In the absence of data, an eloquent negotiator is often able to obtain their desired outcome, no matter how sub-optimal that outcome might be.
Nowadays, I see data used a lot more, hence the telemetry. A while ago, in response to criticism of Windows telemetry habits, I wrote:
"Telemetry is, by now, a fundamental part of the engineering process. Products that don't incorporate it are going to be clobbered by products that do. Microsoft didn't start this paradigm, but I think they had to incorporate it in order to stay competitive."
I understand that telemetry is still a delicate issue, but the expertise based decision making of yester-year truly sucked for many, and I don't see a viable alternative.