Should League of Legends implement a comeback mechanic?

One thing that stood out to me in dota 2 was being able to comeback due to 2 things:

1. being able to make all allied buildings and minions immune to damage for a couple of seconds

2. being able to spend gold to buy yourself back from death.

Now it doesn't have to be either of those things. However the way league is right now if a team gets ahead there is no stopping them from completely stomping on the enemy team. It's the reason why comebacks are so rare and why snowballing is so strong.