True, AppImage basically just format of portable application. But you could update it on each major update. I only update my Electrum occasionally (when there's new interesting feature or fix serious security vulnerability).
I understand, but considering this process for boring and archaic (from certain point of view). Central software management (maintaining software up to date) is one of the reasons I am using Linux for about ten years. I don't want to know about security problems - I want downstream to do the job and supply updates to users in confortable manner. It has some problems on non-rolling distros (I was using archlinux for long period), but Linux Mint show us, it is possible to integrate Flatpak to system in very comfortable manner and thats what I really like.
But no offense - every technology finds its users and I hope you enjoy using appimage.