Doesn't matter. It's same as any tech. Need to understand mathematics and algos and have great fluency in code. Can't speak for the other guy but I suspect he's same: no amount of skill "aligning stakeholders" and "managing cross-functional teams" is of much use in the business if you're at a prop shop. Have to be able to write code. No "blocked on other team", "Kernel Timestamping API is undocumented" etc.