I just keep thinking "a pink ward would shut down this akali and teemo"

A pink ward is 125 gold. An oracle is 250.

you don't have a problem drinking oracles on a map where you are guaranteed to die?

Have one of the AP champs on your team buy Sweeper. There you go. All stealth champs countered and so are Teemo's shrooms.

Edit: Oracle is extremely overpowered on this map too. You might die, but I guarantee you that enemy Twitch is going to die first.

Repeated Oracles purchases set you too far back to be a viable option for shutting down Teemo/stealthers imo.

Hextech Sweeper is where its at.
Not only does the active screw in-combat stealth and the passive has "**** you Teemo" written all over it, but there is literally not a single wasted stat on that item if you are playing a mage.
It's truly a great AP item.

Another reason is the brush. I've won and lost many games based on how the brush was used, from ambushing a player / team to poking from the fog of war. Wards would completely invalidate the brush, which is not a good thing.

That, and gold is easy to get. Oracles are not all that expensive, when you think about it.

Hextech Sweeper. It has decent stats and you are bound to have someone on your team that can grab it without hurting their build.

How I wish old Sweeper still existed...it was so OP on Soraka.

Because Arma is a completely different game. DayZ was fun while it lasted, but if you had wards on the map, it would almost be as bad as the game was when it got hacked every day.