Almost all of GCC's development is done by employees of big corps, often as their sole job. Red Hat, IBM, etc.
The Linux Foundation was intended act as the backstop here, but it is losing that focus, and I'm not confident that it will remain a trusted steward in the future.
For now, and to the point here, the sheer number of meaningful contributors to Linux is what differentiates it from things like Java and .NET. GCC is somewhere in the middle: less resilient than Linux, but more than Java.
A voluntary samaritan committing yet another driver for this IBM entreprise controller, or that Facebook file system?
Linux is "community-of-big-corps"-developed.