The whole point is that you can build a working container image and then ship it to a registry (including private registries) so that your other developers/users/etc don’t have to build them and can just run the existing image.

Agreed, we still do this in the areas where we use Docker at day job.

I think the mileage with this approach can vary depending on the languages in use and the velocity of feature iteration (ie. if the company is still tweaking product-market fit, pivoting to a new vertical, etc.).

I've lost count of the number of times where a team decides they need to npm install something with a heavy node-gyp step to build native modules which require yet another obscure system dependency that is not in the base layer. 😅