A colleague insists on heat plates within the microwave,commonly stacking up to 4 plates next to no food on them? I wonder is this ok? Is it doing any damage to the...

I wonder is this ok? Is it doing any damage to the microwave?
Answers:    I other warm plates this means of access. However, I always trickle a highly small amount of water onto respectively plate before stacking. No break and good, hot plates that in recent times need a rapid wipe.
its fine. maybe he is sterilizing them. for not dangerous measure