I was taught that dry mounting was the worst way to handle prints when conservation minded.
Paper is in need of breathing space ie it expands and contracts and it cannot do that if dry mounted. It might be alright with RC paper since it is plastic, lol. Not sure. It was a long time ago and once I got into the habit of two little pieces of acid free tape to attach the print to the back half of my mats, that has been my only method.
Of course, the mat needs to be acid free also.