What do you mean "left behind"? Are you saying people will actually gt "left behind" or just that people will _feel_ like they're left behind?
At this poitn you can find tools that can make demos easier to build or get you further in a hackathon, but Rails embodies "Slow is steady and steady is fast." If you're trying to build something that will stick around and can grow (like a startup outside of the latest VC crazes) then Rails will arguably do better at keeping your tools relevant and supported in the long run. That is, assuming you're building something that needs a steady backend for your application.
At this poitn you can find tools that can make demos easier to build or get you further in a hackathon, but Rails embodies "Slow is steady and steady is fast." If you're trying to build something that will stick around and can grow (like a startup outside of the latest VC crazes) then Rails will arguably do better at keeping your tools relevant and supported in the long run. That is, assuming you're building something that needs a steady backend for your application.