I have noticed that a few different commentaries they say that the reason a team lost their match up was because they didn't have enough visibility of the map. Is it truly that important to see the whole map?
Can you tell me what roles are supposed to do the warding and when and how they go about it?
Best Answer
Apply it to real world and you'll immediately see the benefits of map visibility. How well would we be equipped for war without radars? How valuable is stealth warfare etc?
Being able to sneak up on opponents is too strong of advantage to let any team have for free. Wards allow you to prepare for incoming ganks, to move quickly on map objectives, and even for some champions provides as a way for escapes.
The most obvious understanding of this comes to bottom lane. As a support, your job is to let you carry farm as much as humanly possible without being interrupted. Wards allow you to watch for incoming jungle ganks, roamers, etc.
The other role whose main job, among clearing neutral minion camps, is warding, would be the Jungler. As the bottom lane support is, quite frankly, stuck at bot lane, the roaming Jungler has a better chance of passing through areas that could use wards that would make or break a game. Until lane phase is over and the support starts to move around, it is important for the Jungler to ward the rivers to prevent ganks on top and mid, attempts on dragon and baron, counter jungling attempts by the enemy, as well as to provide constant vision of the other team so that your own knows when it is safe to pursue certain objectives.
For example, a ward in their jungle near the Blue Buff would show you that the enemy Jungler and/or Mid is currently not killing it and it is somewhat safe to steal it. At the same time, if the ward shows you both their Jungler and AP Carry are at the Blue Buff, it is safe to do a 3/4/5vs2/1 team fight on bottom since you know they will be receiving no reinforcements.
Seeing the map just allows you to do/access/defend/attack safer, smarter, more efficiently.