But that isn't true of many other legit open source projects. As others have pointed out: mobile apps, browser extensions, native apps / libraries, etc. are much more readily accessible when distributed as binaries than as source. Most open-source projects don't want to require everyone to learn how to build from source before they're allowed to use the project, and I think that's a good thing.

One other note: last I checked, the auto-generated ZIP/TAR downloads (for tags or master) were completely broken for any repo that uses submodules.