Certainly there's a complexity argument to be made, because you don't actually need compression just to hold a bundle of files. But these days zip just works.

The perf measurement charts also make no sense. What exactly are they measuring?

Edit:

This reddit post seems to go into more depth on performance: old.reddit.com/r/selfhosted/comments/1qi64pr/comment/o0pqaeo/

I didn't even realize random access is not possible, presumably because readers just support it by linear scanning or putting everything in memory at once, and comic size is peanuts compared to modern memory size.

I suppose this becomes more useful if you have multiple issues/volumes in a single archive.