As I said, they mention having a problem where each service depended on different versions of internal shared libraries. That indicates they did not need to update all at once:

  > When pressed for time, engineers would only include the updated versions of these libraries on a single destination’s codebase.
  > Over time, the versions of these shared libraries began to diverge across the different destination codebases.
  > ...
  > Eventually, all of them were using different versions of these shared libraries.