When you think about it, Google's integration of YouTube with Stadia can actually be super-successful, and cause some concern for Sony and Microsoft without a similar platform that reaches billions of users a month. Having the ability to live-stream with a click of button and having participants join in at a click on a major social media streaming platform, can be a game changer in the world of live-streaming for YouTube [gamer] personalities and new beginners. Just imagine multiple (possibly hundreds) users live-streaming immediately / synced on a particular game without the need for fussy PC or game console settings between users systems or the need for personal (or 3rd party) servers that manage multiplayer gaming sessions, users, and the streaming component. Everything will be a self-contained platform by Google, the users simply click, join, stream and play without much hassle. Mind you, I'm talking about this in the most optimal situation where users have minimally a 30-50 mbps connection, the Google controller, and Stadia gaming services. Think about all the pitfalls (i.e., gaming sessions/system crashes, is everyone system/game up to date, synchronization issues, server down, etc.) that live-streaming of games, especially multiplayer, go through. Something like the Stadia platform can relieve a lot of those burdens.
Then the question becomes, how does Sony, Microsoft, and Nintendo leverage or create a live-streaming service as robust as YouTube? I'm almost certain Google isn't going to integrate their competitors services into their systems... not in the fashion Stadia platform is offering.