Developer efficiency is notoriously difficult to measure and prone to all sorts of biases. Perhaps the key word in your sentence is "I"?
I've done my fair share of both Java and Ruby web development, and without a doubt, I was much faster writing Ruby.
For non-trivial Java apps, startup time was > 20 seconds. That kind of REPL while developing kills productivity and developer satisfaction.
The last Java app I wrote had more lines of configuration than my first Rails app had lines of code, at equivalent complexity.
The first Java job I had required a full-time script writer, a DBA, and someone to keep the web server up. In Rails, that entire team would have been shrunk by 75% (mind you it didn't exist back then).
I do work in other languages. For machine learning, Ruby's speed is a killer except for toy data sets, so I have used Octave and Python. When it comes to the web though, Rails really did do many things right, from a sane MVC, default ORM, helpers and migrations. There are times execution speed trumps development speed. For fast dev on web apps, Rails really was cutting edge and for those with an investment it can still be a better trade-off than doing something in Go.
It still seems as though these frameworks are all playing catch-up, with e.g. things like migrations.