I had the same thought. I was thinking perhaps its like language where at one point no one knew any common words but nonetheless formed a common understanding.

But Im not sure that works here. Besides I still dont see how feeling is necessary to accomplish this goal. Youd have to merely teach a robot to emit some unique symbol which another robot interprets as "that hurt".

And pain/empathy is just one thing. Theres a lot more to conscious experience. Seeing/hearing/feeling good/bad, etc