Lead mod for currently airing shows: 12 Monkeys, Big Bang Theory, Bosch, Dynasty, Fuller House, The Gifted, Grey's Anatomy, How to Get Away with Murder, Legion, Midnight TX, Mindhunter, The Orville, The Resident, Star Trek: Discovery, Van Helsing, Younger
Yeah, it happens, especially on long-running shows like Grey's. The shows don't often go with what an actor might pitch but they may go with it if they think it's a good idea. April's storyline about losing Samuel was pitched by Sarah Drew.
Capshaw may not have wanted to use Spielberg as a leg-up and made her way on her own merit. However, if Shonda ever wanted to break into movies, she probably won't be getting business from any Spielberg productions now.