Yes, I saw it the other day - though of course being dealers they are less fussed about long-term degradation of coins via surface contamination (the coins have long ago been sold by the time that would have an effect), but granted, edge knocks are an immediate effect for anyone! Provided the trays are wide enough that they can fully get their fingers around the edges of the coin before picking it up, that's pretty important. otherwise it's almost unavoidable for fingers to intrude over the rim.
I did raise my eyebrows when they mentioned that wisps of cotton fabric from cotton gloves could cause hairlines. I can't ever see how that could happen!
Also it depends on the metal - lustrous copper or bronze need a lot more care in handling than say, toned silver or gold.