To answer Steve's questions, if you can call them that:
I've been watching videos of Molly and observing the style.
I have a sister, a former professional dancer, whose joint injuries are related to over-doing it.
I have done folk dancing and was repeatedly told to take small steps.
You can read about the podiatrist's to me comment upthread.
I take exception to the idea that tradition or the wishes of entertainment promoters are more important that a dancer's long-term well-being.
The Molly dancers should ask to dance on grass, on a stage, on a Marley floor or maybe even on plywood. Not on concrete.
Believe me, what with the costumes, the make-up, the music and the patterns in the dance, people will watch Molly even if the dancers stand up for themselves and dance wisely. That means to dance without pain, without exhaustion and without damage to joints.