Never understood this argument. Have you tried to club something? If you it enough to cause serious damage, then there will be blood everywhere. Not even talking about common style of maces like spiked or flanged.
It is a joke, a DND joke to be exact.
In early editions, there were a lot of restrictions on equipment in the classes, and with the clerics, one of them was that they could only use blunt weapons, and the "in-world" reasoning was... that because a cleric hates to make people bleed and cause unnecessary pain they used blunt weapons to not make a mess... yes, it is stupid.
And this gets even more stupid when you consider that you could be a cleric of an evil god, and this restriction was still in play for the same reason, nowadays it isn't used anymore.
It's because it's a corruption of the original concept, which was that priests were generally forbidden weapons of war, and thus began to carry heavy blunt instruments, like a weapon-quality staff, club or mace disguised as a walking cane or walking staff. Furthermore, priests followed the principle of [sine effusione sanguinis], literally "shed no blood", and such meant that rounded maces and similar weapons (rather than spiked or flanged maces) would be used to bruise and break bones, but not shed blood externally, though they were no less lethal (and in fact more lethal in a great many more situations, due to how they interact with hardened targets, and how little soft armor would resist such blows on their own). They weren't entirely restricted from edged or pointed weaponry, however, due to both things like daggers and their gods' personal weapon of choice, which is why the "Favoured Weapon" system existed.
Mechanically, it ensured that the best weaponry was wielded by the full warrior of the party, and that the cleric, while still strong in a fight, had to utilize magic to stand toe to toe with the warrior, to balance out the casting in full armor without restriction as well as access to strong healing, buff, and combat magics.
But Hasbro and idiots that have no concept of history or why things are the way they are decided to throw it out the window because they thought it was stupid.
