Lane Pushing Tactics

[Ashe]

It opens options. If we create a scenario where we have creeps against multiple towers, then not only are we having some time of getting a small amount of tower damage (which on its own isn't much but also builds over time), we also now have the option to appear at any of these locations for a quick skirmish on their tower(s). Additionally, by pushing different lanes up that far, we deny THEM the opportunity to do the same. Furthermore, by doing this, we restrict their map presence so that we can farm the entire jungle, as well as their side of the map, while they have to sit at towers and clear the waves. During this time, we can safely farm jungle, control buffs, control dragon and/or Baron, or even reward key areas in preparation for a push in another area so that when they move to defend said area, we know how many and which path they are taking, which wins the information war. Then someone else could make a quick strike at another tower if we know they've sent their full force to try to surround our top. Just one of the scenarios it opens up.

But basically that, it opens up options and map control. (EDIT: The argument of "If we can't take the tower, then pushing the lane is pointless" is very analogous to "If we can't get the kill due to summoner spells, then don't waste your time on the gank". We've already outlined how a gank can be successful with no intention of actually getting a kill, and how it isn't a fail-gank just because they didn't die.)