Steel stickers! Not in my shop. A steel sticker is too hard which will deliver more impact. Impact is absorbed by the struck face and will cause damage.(hence the mushrooming you mentioned that I don't get)
The softer impact of a wooden mallet provides sufficient driving force for wood cutting tools and driving pegs without causing damage to them.
I don't care what the Japanese or anyone else did a 100 years ago, that doesn't make it right.