People keep repeating that like it's some commercial gimmick, but what does it really mean? How is Rails or rails-api not suited for APIs? What's lightweight? What's easy?
And more particularly since you seem to know about this, what other option would you favor?
Well Sinatra seems pretty nice. I'm a node.js developer so I use Restify and Express. But I practically build api's exclusively. I've spent a lot of time cleaning up after terrible Rails applications. Replacing bits that are too slow or difficult to maintain with smaller more nimble node applications.
It means he's a node troll. They take a shot at the dominant frameworks any chance they can get. Node trolls have reached the level of obnoxious arrogance that early Rails developers were once mocked for. Don't feed the trolls.
It's about using the right tool for the job. Most developers never seem to understand that. Everyone seems to want the same magic bullet for everything.
And more particularly since you seem to know about this, what other option would you favor?