At least going by their own CV, they've mostly written what sounds like small scripting-type programs described in grandiose terms like "data warehouse".
When I talk with people in the space, go to meetups, present my work & toolset, I am usually one of the more advanced, but usually not THE most, people in the conversation / group. I'm not saying I'm some sort of genius, I'm just saying I'm relatively near the leading edge of how to use these tools. I feel like it's true.
https://www.linkedin.com/in/benshoemaker000/