I recently switched from etesync to a self-hosted solution and didn’t want to install a full Nextcloud on my tiny home server just for that. So I initally tried out radicale as well, but I didn’t like the default user handling (no authentication at all) and the project had been unmaintained until very recently (two weeks ago). I switched to baikal then and I am quite happy with it so far.
To put it in simpler terms, I’d say that containers virtualise only the operating system rather than the whole underlying machine.I guess not then.