First of all they make the user dumber. Instead of learning something new, you blindly “compose pull & up” your way. Easy, but it’s dumbifier and that’s not a good thing
I don't like this Docker trend because, besides what you've said, it 1) leads you towards a dependence on property repositories and 2) robs you from the experience of learning Linux (more later on) but I it does lower the bar to newcomers and let's you setup something really fast. In my opinion you should be very skeptical about everything that is "sold to the masses", just go with a simple Debian system (command line only) SSH into it and install what you really need, take your time to learn Linux and whatnot.
there is a dangerous trend where projects only release containers, and that’s bad for freedom of choice (bare metal install, as complex as it might be, need to always be possible) and while I am aware that you can download an image and extract the files inside, that’s more an hack than a solution
And the second danger there is that when developers don't have to consider the setup of a their solution the code tends to be worse. Why bother with having single binaries, stuff that is easy to understand and properly document things when you can just pull 100 dependencies and compose files? :) This is the unfortunate reality of modern software.
Third, with containers you are forced to use whatever deployment the devs have chosen for you. Maybe I don’t want 10 postgres instances one for each service, or maybe I already have my nginx reverse proxy or so
See? Poorly written software. Not designed to be sane and reasonable and integrate with existing stuff.
But be aware that containers are not the solution to selfhosting-made-easy and, specifically, containers havebeen created to solve different issues than self-hosting!
Your article said it all and is very well written. Let me expand a bit into the "different issues":
The thing with Docker is that people don’t want to learn how to use Linux and are buying into an overhyped solution that makes their life easier without understanding the long term consequences. Most of the pro-Docker arguments go around security, reproducibility and that’s mostly BS because 1) systemd can provide as much isolation a docker containers and 2) there are other container solutions and nobody cares about them.
Companies such as Microsoft and GitHub are all about re-creating and re-configuring the way people develop software so everyone will be hostage of their platforms - that's why nowadays everything and everyone is pushing for Docker/DockerHub/Kubernetes, GitHub actions and whatnot. We now have a generation that doesn’t understand the basic of their tech stack, about networking, about DNS, about how to deploy a simple thing into a server that doesn’t use some Docker BS or isn’t a 3rd party cloud xyz deploy-from-github service.
Before anyone comments that Docker isn’t totally proprietary and there’s Podman consider the following: It doesn’t really matter if there are truly open-source and open ecosystems of containerization technologies. In the end people/companies will pick the proprietary / closed option just because “it’s easier to use” or some other specific thing that will be good on the short term and very bad on the long term.
Docker may make development and deployment very easy and lowered the bar for newcomers have the dark side of being designed to reconfigure and envelope the way development gets done so someone can profit from it. That is sad and above all set dangerous precedents and creates generations of engineers and developers that don’t have truly open tools like we did. There’s LOT of money into transitioning everyone to the “deploy-from-github-to-cloud-x-with-hooks” model so those companies will keep pushing for it.
At the end of the day technologies like Docker are about commoditizing development and about creating a negative feedback loop around it that never ends. Yes, I say commoditizing development because if you look at it those techs only make it easier for the entry level developer and companies instead of hiring developers for their knowledge and ability to develop they’re just hiring “cheap monkeys” that are able to configure those technologies and cloud platforms to deliver something.
Successful cloud companies are not longer about selling infrastructure, we're past that - the profit is now in transforming developer knowledge into products/services that can be bought with a click.