For as much as you're right, your taking a very narrow short-term view of productivity.
The maintenance demands for using a heavy, evolving framework and a large graph of churning dependencies are tremendous and perpetual. While you can make meaningful wins on delivery time for a new feature, once "you are set up reasonably well", you've impliclty introduced new costs that don't apply to "vanilla" code that stays closer to established standards and only includes code it actually uses.
That's not to argue that vanilla is strictly better (both have a place), but just to acknowledge a latent but significant tradeoff that your comment seems to ignore.