The game has 4 people, 2 roles that do damage. If you leave the Tank and Technical by themselves, and the enemy team doesn't also do 2 Damage top/ they have someone who can do actual damage in both lanes, they lose. They don't really have the damage to do more than stall for one of the 2 of you to come down to help. If you don't go down and work with the lower lane, they won't be able to get kills or get any progress unless the other team messes up heavily.