That part is almost right, but also a little confused.
He built GoSnaps, which is a geo-enabled gallery with: No chat, few messages, few writers, many readers, medium amount of reads, large messages, not time-dependent. (Not even user state.)
Then he contrasts that to the failure of GoChat, which is a geo-enabled chat with: Many-to-many chat, many messages, many writers, many readers, many read operations, small messages, very time-dependent.
The performance profile between these two things is wildly different and the way he's patting himself on the back over what amounts to half knowledge is pretty disgusting.
Edit: Wow, he did update it and he's only defending his bullshit with more half-knowledge. At this point i'm ready to call him a liar, just over this claim: "My conclusion is that both apps are very similar in terms of scalability complexity."
This is why I don't see the point of moving over to Elixir. Rails has ready-to-go and battle tested "modules" that you can pop in and go.
If I used Elixir now, I would have to wait for the community to build something battle tested or I can home-roll my own Elixir authentication. The Poster above just said, "It's a pain particularly user authentication."
That said. A chat application is really, really well-suited to Elixir.
I think no-one builds their apps this way yet so maybe it needs more explanation.
The grand parent was asking about a template/hackable starter kit with batteries included. That setup of ueberauth is the best I've found sadly.
I have used it for multiple projects and it gives a huge head start compared to starting from zero. Signing up, logging in, resetting the password, uploading, etc all seem like easy work but when you pile them all up you can easily spend a week just getting to the point where you are within minutes of cloning the starter repository.
However the failure of GoChat is not relevant to Pokemon Go. While GoChat might have done something very wrong comparing 1mil users to an app with tens of millions of concurrent users is invalid. Pokemon Go would be a NoGo running on a single Node.js machine without any sort of balancing.