Sure, they were encouraging usage of the docker hub, but it's been at least a couple of years since they started pushing on the other way, when they introduced the first rate-limits.

If everybody did a fair-use of the Docker Hub maybe we wouldn't have the rate-limits in the first place? But I think we all learned that won't be happening in the open Internet.

Setting up a pull-through cache is pretty straight-forward, you can find the instructions in Docker's documentation: https://docs.docker.com/docker-hub/image-library/mirror/