Most containers don’t package DB servers, Precisely so you don’t have to run 10 different database servers. You can have one Postgres container or whatever. And if it’s a shitty container that DOES package the db, you can always make your own container.
that those images are configured according to your actual end-users needs, and not to some packager’s conception of a “typical user”: do you do mailing? A/V calling? collaborative document editing? … Your container probably includes (and runs) those things, and more, whether you want it or not
that those images are properly tuned for your hardware, by somehow betting on the packager to know in advance (and for every deployment) about your usable memory, storage layout, available cores/threads, baseline load and service prioritization
You can typically configure the software in a docker container just as much as you could if you installed it on your host OS… what are you on about? They’re not locked up little boxes. You can edit the config files, environment variables, whatever you want.