On the contrary, I've found that picking up an application written in Rails by someone else is quite easy. Far from building walls between developers, I think a good framework like Rails encourages communication.
This is one of the reasons I'm developing my current application in Rails, rather than just rolling my own framework. I'd probably have more fun building my own system, and there are certainly frustrating bits about Rails, but I like the fact that I can, in fact, work with other people.
Frameworks built by communities of passionate coders are, I think, fundamentally good, because they enable sharing, which is essential to any long-term project.
Daniel