Practicing on cotton yoga rug isn´t something new - there is almost nothing special about it. But at the same time, it is becoming special again because it was forgotten for some time...
Back in the days, when Krishnamacharya was teaching - there were no yoga mats, they practiced standing sequence on the floor and they would grab a rug or blanket for seated postures.
I know, everything is evolving and you can not stop the technology, but sometimes you realize that the technology is harming us more than actually helping us.
Thats what happened with yoga mats vs. yoga rugs.
Plastic yoga mats were introduced to to market when yoga started to be part of fitness industry...and you know how it is working in the gym, you come, practice in sneakers, sweat on the mat, wipe it up with towel and go home.
These mats were probably never washed...and that‘s what we have adopted.
To conclude, yoga rug is nothing new, nor any special technology is used.
By practicing on the rug we just go back to the basics!