A long time user of Open Media Vault here. I used it since the very first stable release.
I see a lot of people here missing plugins which existed in earlier releases. While I do understand that it requires a lot of maintenance to keep those plugins alive, it is definitively not an excuse to say 'docker' and 'if you don't understand it you reached a dead end'. That's not how that works. Heck, why would someone use OMV at all at this point? You could also point to a basic howto explaining how to install Debian with Samba or something like that and halt development at all "does the same, less maintenance". I believe NAS systems of this kind are made for ease-of-use and setup, without letting a novice to deal with the command line hassle, leaving them with potentially dangerous and insecure setup.
Meaning some novices got a docker container working using a howto only is a far cry from a properly configured and a secure system, which is especially important as a use case of a NAS is having your data available everywhere. Docker is a advanced system - which when configured correctly is great - but if not mistakes are easily made putting the whole system at risk. This is something the developers should think of and design around.
My opinion is that the plugin ecosystem in OMV needs a big overhaul. Using Docker containers is a good thing (persistence between systems), leaving the rest to the user is not. OMV Should have it's own interface of dealing with Docker (automated container setup) and a forward-compatible way of creating setting pages for those plugins. I take the DAV plugin as a example. In earlier versions, within the web interface, one was able to control shared folders and user permissions with a few clicks. Do do this now, one needs to recreate a container every time someone needs to add or delete a shared folder (Docker doesn't allow live changes in mountpoints) and needs the command line to add new users. But what if the user just wants to grants a household member access which already has a OMV account? Ask someone for his/her password and key it in for htaccess? Not a smart move. I can come up with lots of these things, but I feel like this is a bad decision.
When OMV controls Docker under the hood with a standardized way of creating WebUI addons, these things can be automated while the maintenance burden is minimized. For example, how could someone check against OMV's user database for access control in a app running in a Docker container? It doesn't even offer an (REST) API for that. Sure, someone can build one. But I feel like this is stuff that belongs in the core which should just work. Especially now that more and more things are expected to run in Docker.
I'm not saying OMV is bad. It just hurts me that more and more support and convenience (well-integrated plugins) is dropped, people are left with - in most cases - no clues and the ambiance seems to be 'good luck'. This is not what a product of this kind meant to be. It should be a nicely integrated package which requires little knowledge to setup, even for those who are less 'educated'.
Remember, this is only my opinion. But I felt like I needed to mention it.