Because of a lack of features? It doesn't even have IK so I would argue Blender is in fact easier to use (as in, will get you to the result faster even if you need a bit more time to learn the interface).

This has pre-built poses, props and a bunch of other easy to use features. This is classic hacker-news ‘Less intuitive and more complicated X is better because I already know how to use X’

I must have spent a hundred hours in Blender over the years, and I'm still not competent enough to do even some of the most basic things on my own when I pick it up.

Blender is an amazing project, but I would not suggest it as an alternative to OP's tool if asked by someone who practices drawing and has zero Blender experience or interest.