Frameworks like Rails come with a constant upgrade overhead cost. If you're a solo developer, or even a small (<5) team, that overhead is likely to dominate your development time. Also, the main benefit of the framework (keeping a sane structure while multiple developers' are making code additions) isn't any better than just ad-hoc sharing standards and practices amongst the team. So, it's better to use a simple nodejs server or even plain old php pages.

Once you get past a certain number of developers, the constant overhead is something that still needs to be dealt with, but relative to the human-hours of your entire team, it's much smaller. Also, the team is no longer able to ad-hoc share architectural goals, and so having a framework in place that enforces them scales much better.

Starting with a framework is tempting because everyone thinks that they'll get big. But what if you don't? Maybe it's better to have a little passive income than crash and burn. On the other hand, if you do get big, the tradeoff is that you'll need to rewrite with a framework. That's another opportunity to crash and burn, so it's debatable which is better. Personally I think that Twitter has demonstrated how to do the "start dead-simple and rewrite as the team grows" method.