While that would be ideal for compatibility reasons, like Illothar said, it’s not possible for every application. Even if it were, sometimes it can be incredibly hard to find any relatively modern version of a library compiled for such an old version of Glibc. Also adding, since static compiling seems to be very discouraged in the Linux community, it’s almost guaranteed that at least one necessary library in a large program doesn’t support static linking at all and probably won’t even compile, making that a non-option for many cases as well.
Imo the closest compromise would be to have another optional flag in the desktop file, such as “X-AppImage-GCC”, so that the AppImages which can’t exist on GCC 2.23 at least have a standard way of communicating their compatibility instead of either crashing or having to implement their own warnings, which ultimately just puts unnecessary work on the developer