Creatures like Looter il-Kor, Putrid Imp, Oona's Prowler, and Fauna Shaman can first get your reanimation target in the graveyard, and then sacrifice itself to your Recurring Nightmare to complete the combo
This is also pretty hard to come by since its also reserved list, so theres an even bigger audience for this
Now, instead of surrendering a unique strand of the shared language which unites Magic players of all eras, you strengthen that connection AND create the design space for a bear-themed deck to connect together mechanically rather than simply being random 2/2s with similar art
Ydwen Efreet is not officially Reserved, but its the only non-RL Arabian Nights rare to never see a second printing during the subsequent 30 years
And in a year where WotC could easily have their hands full trying to revive tournament play and keep LGSes afloat, its good to know that dark clouds could have an etched-foil lining