"Battle" is something that has been shot down befoore - albeit, not multiplayer wise.
If Multiplayer were added (which usually isn't something a small team for a singleplayer-esque game does)
I'd imagine it'd be more so, co-op, 1-4 (pushing it) and the essential reasoning would be specialization and multitasking.
Example
Making it so in Co-op/multiplayer, and further down the developement road
Where friends/players/teammates/etc - would have to choose "Armorsmith" or "Weaponsmith" or "Miner" kinda things.
One would be off mining or tending the counter.
The others would be toiling away at the hammer, and there'd likely be a 2nd anvil - or potentially Both buildings we currently see would have to be owned, and the 3rd or 4th person (the miner) would have to help both locations, running back and forth (So instead of Str ever being a stat the Miner would use, he'd primarily be all charisma and agility - while the other two were mostly str and int, with a hint of agility)
The only way battle would fit into that, if it was strictly a "Who can get and fill the requests of the most customers in a day/week/month"
But Bosses, Monsters in the cave, "battle" with us wielding some form of weapon - Has been mentioned, and "shot down" (Paraphrase: "Simple casual blacksmith game, maybe if I make another game I'll put that in there")