Nearly 6,000 people will soon pack their bathing suits and their linen suits and descend on Miami Beach — not for vacation, but for one of the marketing industry’s buzziest conferences. Marketing doesn’t exactly suffer from a lack of conferences. From tightly curated executive retreats to sprawling trade shows, the calendar is saturated. And yet, in just three years, one newcomer has managed to carve out meaningful space and momentum by positioning itself squarely in the middle.