[@CaptainXtra](/forums/generals/topics/gun-discussion?post_id=5241533#post_5241533)
SMGs were very popular before assault rifles were invented. But since assault rifles are so good, SMGs went out of fashion. Still, they aren't dead at all. In some militaries, vehicle crews still use them, though they are being replaced by SBRs or PDWs. Compact SMGs are still useful for e.g. bodyguards. Pistol caliber carbines are gaining popularity in the sporting world.