For a glimpse of "what is possible", take a look at TkInspect (1), a set of gems that I'm working on that provide some of the goodies of that GUI, like an interactive, graphical console, a live inspector, a class browser or turtle graphics.
At the moment it's not more than a toy, but it does definitely show what can be done.
Ruby has no such thing: it's pretty much only used for Rails and plain-jane Unix scripting. It's fair to judge the language in context of its actual applications.
Most, not all: https://www.gnu.org/software/smalltalk/manual/html_node/Over...
Although it looks like somewhere along the path with the "new" graphical browser they dropped the tag line "Smalltalk for those who can type".
Rails is a monster, and historically pretty poor ruby code quality INMHO. That said, ruby does indeed miss an "image" concept, but is quite dynamic and object oriented. Some smalltalk patterns would work well with ruby, I think.
There's also (the abandoned?) maglev ruby on top of gemstone/s object db for smalltalk.
Rails is extremely far from those dynamic Smalltalk application environments. Nothing is live. Object graphs are built up to serve a single request, then torn down immediately — a bizarre kind of kamikaze OOP. To me it's the worst of Smalltalk and PHP in one, as all the interesting aspects of dynamic typing are wasted and just become a source of bugs.