I'll answer your question of why with your own frustration - bare metal is difficult. Every engineer uses a different language/framework/dependencies/whathaveyou and usually they'll conflict with others. Docker solves this be containing those apps in their own space. Their code, projects, dependencies are already installed and taken care of, you don't need to worry about it.

Take yourself out of homelab and put yourself into a sysadmin. Now instead of knowing how packages may conflict with others, or if updating this OS will break applications, you just need to know docker. If you know docker, you can run any docker app.

So, yes, volumes and environments are a bit difficult at first. But it's difficult because it is a standard. Every docker container is going to need a couple mounts, a couple variables, a port or two open, and if you're going crazy maybe a GPU. It doesn't matter if you're running 1 or 50 containers on a system, you aren't going to get conflicts.

As for the security concerns, they are indeed security concerns. Again imagine you're a sysadmin - you could direct developers that they can't use root, that they need to be built on OS's with the latest patches. But you're at home, so you're at the mercy of whoever built the image.

Now that being said, since you're at their mercy, their code isn't going to get much safer whether you run it bare-iron or containerized. So, do you want to spend hours for each app figuring out how to run it, or spend a few hours now to learn docker and then have it standardized?