There would be some sort of process for coming to a decision on choices that have broad impact. The same way there would be a process within a team when differe

There would be some sort of process for coming to a decision on choices that have broad impact. The same way there would be a process within a team when different individuals disagree on direction. The problem with a top down approach is that the architect doesn't actually know what is actually needed by teams. They're too far removed from the day to day. So you get a uniform but generally suboptimal set of technologies.