The question in my mind then becomes "what job is ruby the right tool for?"
If the reason not to use better principles is because Ruby makes them painful, rather than there's something about the domain that makes them a bad idea, why choose Ruby to begin with? Presumably the ecosystem.
I agree with emphasizing caution, but I definitely think it's worth being at least somewhat weird with your Ruby to get as much as you can from the best of both worlds, the Ruby ecosystem and functional principles.
If the reason not to use better principles is because Ruby makes them painful, rather than there's something about the domain that makes them a bad idea, why choose Ruby to begin with? Presumably the ecosystem.
I agree with emphasizing caution, but I definitely think it's worth being at least somewhat weird with your Ruby to get as much as you can from the best of both worlds, the Ruby ecosystem and functional principles.