I think the desire to sort poses by difficulty could be widespread, but to fulfill it, there is a technical obstacle to overcome: someone would have to sort and rate the poses by difficulty, and difficulty is also highly subjetive, and influenced by the chosen method and exact aesthetical goal of the individual exercise.
A first step towards ordering the images by difficulty could be to include a rating scale for each image at the end of the exercise, when all the images included in the exercise are presented again, so participants can leave their individual subjective rating.
It would still take a very long time to gather enough data to start sorting such a huge database in a meaningful way, and there could be still a few problems with data bias. Naturally only data from people, who rate images could be gathered, and the mood of people finishing a study could produce outliers that skew the overall pool.
Next step after collecting lots and lots of data about subjective impressions of the difficulty of individual images, the question how to meaningfully use this data would have to be decided. How would for example newer images with fewer overall votes be compared to older images with a lot of votes?
I find the desire to rate and/or sort images by difficulty understandable.
I suspect the technical challenge in implementing such an option to be at least cumbersome, and would not neither want to volonteer to such a task, nor to pressgang anyone else into doing it, but it might be doable.