Oh no, Stadia failed because its business model doesn't really make sense. And Phil doesn't really understand where Stadia's real potential can thrive. He definitely is an expert of the traditional gaming market, but he doesn't really understand how network effects in Google work or where online gaming service is heading.
For the user side, you need decent internet connections and to pay $40~$60 per title. The value proposition is that you can play on a powerful machine in the cloud without paying significant upfront costs, but its inventory is extremely limited and at the moment Google decided to take an intentionally ambiguous position on its commitment, so there was a risk that you're going to lose your ownership on those games. And you also cannot sell your titles on used markets. The pay-per-title model only works if this grants you full control of the title. I think only subscription models like game pass make sense for this kind of streaming service, but Phil looked afraid of bringing too much disruptions to traditional game publishers' business model so made lots of compromises here. This is definitely the first reason of Stadia's failure.
And for developers, they made a significant mistake; instead of making it a plausible platform for everyone, they simply put tons of cash to a handful of AAA developers. This didn't work of course because they're going to release their games on other consoles and Google doesn't have enough negotiation power to have them exclusive on Stadia. The result is a simple failure; overall inventory became much smaller than it could be while it failed to deliver any significant exclusive titles.
Compared to this, Nintendo did it very well on making Switch a developer platform. It's not fully open but still it's considerably more open than what they did in previous consoles. And this gives Switch a very unique value proposition of being the only handheld gaming console (at least before Steam deck) which can play a significant fraction of indie/small developer's games.
There are lots of example cases where an interesting indie game gets skyrocketed by midnight thanks to some big name streamers who decided to play it. What if Stadia was able to have one of them (limited time) exclusive to their platform. Google owns YT so it is in a much better position of negotiating with those creators. And they could integrate ads and payment systems so gaming could be just one click away and developers can get a very precise performance of their ads and attribution from creators.
I still also don't understand why they didn't really plan to integrate the Play store and Android ecosystem. There are significant demands of playing mobile games with a keyboard, a mouse or a controller and on a big screen. The mobile gaming market is dominant not because it's convenient to play but because the mobile market is big. AAA title developers still don't consider it an option because of its form factor and limited controls (and some minor technical issues but not really a fundamental blocker), but Stadia could solve that problem and deliver the Play store to every possible form factors. But they didn't do that. I heard that Google will keep streaming infrastructure and its team that runs Stadia, so there might be some hope that this idea could be realized in the Play store though.