[Crinus]

> Their app bundles are not binaries, they are a directory structure.

Yes, but on Linux no file manager understands directories as bundles (except perhaps GNUstep's GWorkspace).

> Also I don't really understand why anyone on Linux would want this.

Because they want to distribute binaries themselves or via a 3rd party distribution site (ie. not part of a linux distribution) without having the user compile the code themselves (either out of convenience or because they do not want or cannot distribute the source code).

Having said that this is mainly useful in case you want to distribute a single binary that supports multiple architectures. Almost everything is distributed in archives (even self-extracting archives can be shell scripts - although annoyingly enough, software like GNOME's file manager make this harder) so you can use a shell script to launch the proper binary without kernel support.

[AnIdiotOnTheNet]

> Yes, but on Linux no file manager understands directories as bundles (except perhaps GNUstep's GWorkspace).

And the ROX Filer, which sadly hasn't been an active project for many years.

[Crinus]

Which wouldn't really be much of a problem for its users if it wasn't gtk breaking backwards compatibility between 2 and 3 (but that is another painful topic).