1. About Verbosity: that's not common nor idiomatic ruby. You'd much more often see a case statement there, and nowadays with pattern matching. It look like idiomatic python though...

2. About Long Expressions to Detect nil: rails devs have had Object#try fir many ears to avoid that, and &. syntax since ruby 2.3 (10 years?).

3. About Overuse of self, again, clearly the author hasn't done enough python... and that's hardly common, given the many options ruby gives you (ivar access, self-less implicit method calls...)

4. About Collecting Results in Temporary Variables, ruby has supported map/filter/reduce for more than 15 years. This was however quite common code to find years ago from ex-java devs...

5. About Sorting and Filtering in Memory, that's actually the only legitimate problem I can think of. However, I'd hardly consider that Ruby's fault, and more of a superpower of composition of abstractions (datasets to enumerables) which should obviously be handled with care (and perhaps linked against? Does ruboxop support smth of the kind?)

Actual thing I see many times and should be avoided: construction an hash of options first, then pass it as kwargs:

    opts = {
      foo: 1,
      bar: 2
    }
    meth(opts)