I know the advantage of using Serverless technology but I do not understand the real benefit of using SSR app deployed in Adobe I/O. Ad sated in that page the advantage is "More familiar to SPA developers". Is this the only advantage? Can you please help me to understand, any link?
Adobe I/O Runtime is the Adobe's serverless platform that is designed to support 3rd-parties who want to extend Adobe enterprise solutions. For the past 2 years we've been building capabilities to make it as easier as possible. An example if Project Firefly - https://github.com/AdobeDocs/project-firefly.Learning to use I/O Runtime and Project Firefly ensures that you can use the same mechanism to extend Adobe Experience Cloud and Adobe Experience Platform, while reusing all the tools we provide. This goes well beyond of AEM SSR, as you can see. So the questions is not so much Lambda vs I/O Runtime, is more adopting Adobe's tools for handling the extensibility needs or working with some other solution and come up with your implementation.
I'd suggest to ask this question on AEM forums too as I can't speak on behalf of the AEM team.
Hope this makes sense, happy to have meet your team and discuss this in more details.