I think its quite bold to generalise what people may or may not have done without knowing reasoning behind their decision. In my opinion, many of your examples are not a case of overusing the overflow menu, its an adoption of progressive disclosure.
For instance, the gmail toolbar groups and orders the most common actions in response to selected mail. Showing all other possible actions within this toolbar would dilute their importance and visual. Grouping the other, less common options below a descriptive ‘more’ button contextualizes them and keeps them discoverable if not always visible.