Ask What is a freelance skill that requires deep expertise and is increasingly hard to find?

[Brendan]

The world of online work is getting crowded but some skills are still very rare to see. While many people can do basic writing or simple design, only a few have mastered very complex technical tasks. These rare skills take years of practice and deep study to learn properly. Clients are often willing to pay much higher rates for these experts because they are so difficult to find. From what you have seen lately, which specific skill is currently the most difficult to find in the freelance market?