Docker gives you everything you need to cache a build and keep the final image small: multi-stage builds, layer caching, build caching (cache-from/cache-to).
It's more recent of course, so there are a lot of docker images out there that don't contain any of that.
As to my original point, for purely internal purposes you can self-host for a pitiful cost. You're not going to open that to the internet and start running a public registry from it, but it's a trivial setup, easy to integrate with (not abstracted through cloud IAM setups) and cheaper than paying SaaS for it.
It's more recent of course, so there are a lot of docker images out there that don't contain any of that.
As to my original point, for purely internal purposes you can self-host for a pitiful cost. You're not going to open that to the internet and start running a public registry from it, but it's a trivial setup, easy to integrate with (not abstracted through cloud IAM setups) and cheaper than paying SaaS for it.