I am surprised by this shortcoming of Calibre image. I guess the trade is learning how to install calibre vs. learning how to deal with docker. I'd also agree that even if you use docker and installation is easy - for any self hosted apps you are using for a long enough time you end up learning enough about them to be able to install without docker (and avoid managing docker in addition to everything else).
Calibre does have their "book sharing" solution that are built in the software. However it is more like content server. Calibre-Web is a third-party solution that are not affiliated with Kovid Goyal (creator/main developer of calibre). And Calibre-Web is basically browser version of Calibre without requiring other people to use Calibre to access Calibre-Web. So Kovid did not create this calibre-web image from what I understand.
