"Loser", said the person who has never, ever showed to be more than a simpleton in this forum. A magma punch from Sakazuki lacks
representativeness regarding punches's capability of scarring, just like monotremes's eggs don't represent the mammals as a whole.
Punches plus magma leave scars, among many other things. Punches alone don't. And using the former in a debate about the scarring capabilities of the latter is just an association fallacy, and one of the cheapest. Unless Luffy develops magma in his punches and becomes capable of scorching skin plus destroying flesh on a daily basis, nobody should give a shit about how he was scarred.