You have 2 toddlers. You frequently wish to take them to visit friends / parks / supermarkets / libraries / doctors / coffee shops / whatever other places near your location. Such places happen to be 10-20 minutes adult-speed walk from you. Kids are young enough that they cannot reliably walk towards a fixed goal for 10+ minutes, and certainly not at adult speed; they often get either tired or distracted or decide they want to go somewhere else. Kids are old and heavy enough that neither of them can be carried in a carrier. Optimal solution: 2 toddler stroller.
You have 2 toddlers. You frequently wish to take them to visit friends / parks / supermarkets / libraries / doctors / coffee shops / whatever other places near your location. Such places happen to be 10-20 minutes adult-speed walk from you. Kids are young enough that they cannot reliably walk towards a fixed goal for 10+ minutes, and certainly not at adult speed; they often get either tired or distracted or decide they want to go somewhere else. Kids are old and heavy enough that neither of them can be carried in a carrier. Optimal solution: 2 toddler stroller.