Ruby is really good as a language these days, and has only gotten more performant.
Rubocop has gotten wide adoption and has standardized a lot of good practices. By default it's awfully strict.
I worked full-time with Ruby for 9 years across several companies and I solemnly swear that I never saw a single person use method_missing or consider it as anything other than a mostly terrible idea.
Never saw it used once, or even considered once, in actual application code.
Generally that was the case with any of those "sharp knives" or "potential footgun" language features. Monkey patching is another good example. Used to be extremely common and even recommended, but now it is extremely frowned-upon and used only with extreme care/desperation in application code.
The "problem" with Ruby is that it has become kind of a monoculture around Rails. Rare to see it used for anything but Rails these days. People who want a fun casual language are using Python because Python has that booming ML-adjacent ecosystem and a strong foothold in academia/science.