Oh wait, you need to configure your networking bridge differently ... oh wait, the DNS needs this little tweak ... oh wait, you still use this old version from your distros repo? ... oh wait, you must give it this docker volume ...

I can tell you're frustrated from too much yak shaving. But once you become more experienced with systems in general, you'll feel much more comfortable around Docker.

Which is great if you're the person in charge of distributing it, but if the person in charge keeps giving out the "slightly broken" version, everyone will keep fixing it.

Or, and I'm not sure if this is worse, a few people will fix it in slightly different ways, and start distributing those, leading to a weird ecosystem of competing Dockerfiles none of which are quite correct.

Well, what I mean is that once you get your Dockerfile to the point where it works, it will work literally anywhere you've got Docker installed. That is one of Docker's core value propositions. It's very hard to get something "halfway working" in Docker, because you've either got a process running containerized, or you don't have anything at all. "Slightly broken" in the context of Docker isn't really something you run into very often.