There's a lot of cruft, wouldn't you agree? Now, software engineering has a hard time getting rid of it, because we don't know what's going to be cruft in advance. So many promising designs turned out to be just a waste of time. But as long as we can't predict success, we're going to have to go through the motions.
Once you have a working product, it's a bit easier. Maintenance is more predictable. But without R&D/innovation, you're slowly going to fall behind, and that's hard to overcome.
So it might not be impossible that Twitter can keep running with a much smaller staff, but even then it might be the beginning of the end. We'll know in a few years...
Perhaps a union or guild of some description would be in order.