It’s not so much about browsing on steam decks. It’s about the technical improvements Valve has brought to Linux gaming compatibility that has now made full Linux conversion without a Windows dual-boot for gaming a true reality. Once people don’t have to reboot every time they want to start a game they’ll stay in Linux full time.
I think SteamOS might help a bit, but the driving factor might be that Microsoft decided to ditch much of good hardware on their upgrade path to Windows 11.
It seems like a nice one-two punch of Microsoft shitting the bed with Windows 11 at the same time Valve is taking big strides towards making Linux a viable option for gaming. I don’t think you would see this if either happened in isolation.