That's because the placement of a skill reflects the number of companies and projects likely to need it, more than it reflects its difficulty.

Interesting angle on a tech career ladder. I'm more in configuration management / DevOps, and don't have a lot of specific feedback. I was talking with someone this weekend (at WorldCon) whose path was sysadmin > tester > developer. So many paths for us older folks who came in different ways; seems more homogenized for the younger folks.