[ryanbrunner]

Upgrading Rails itself has been relatively simple for at least the last few versions. Between Rails 2 and Rails 4 upgrades were very painful, but that's settled down significantly. You won't necessarily get the new features available with new versions, but especially recently things tend to stay fairly backwards compatible, and when functionality is removed it's almost always moved to a separate library that can just be included with little fuss.

Rails is also a fairly complete package, and you can get very far without additional libraries. Once you do start to bring in libraries it can get painful, particularly if you stray off the path of very popular libraries, but it's nowhere near the Javascript ecosystem.

You're right that Ruby itself won't get you far in terms of a webserver, but the vast majority of web development is done with Rails so in that context it's analogous to thinking of Rails as almost part of stdlib when thinking about web development specifically.