It is a perfect purchase every single game, actually.
It's not necessarily always the first item you should purchase, but you should buy it every game.
When I get autofilled into Support and forget to ward anyway, it's useless to waste the gold.
How is this even an argument? By that same logic, zhonya's, edge of night, bork, and every single item with an active are useless wastes of gold because you forget to use them.
When I'm playing in low MMR and no one looks at the map anyway, it's a waste of gold.
An ignorant fallacy
If I'm playing in high MMR, using information given by the map alone is fine without wards (i.e. if the enemy mid is MIA, you don't need wards to know you should back the fuck up)
Picture this: Mid is MIA, you're pushing top turret. Because you have no vision and mid might be coming up top to stop you, you back off. In actuality, their mid laner is going bot to gank and take bot turret to answer the turret top.
So you've backed off and didn't get to take top turret, and you lost bot turret because you thought mid might be coming to stop you.
Here's another possibility: Your jungler asks you to ward red buff because they're on the opposite side of the map holding lane and can't get to the buff in time. Since you're relying on your yellow trinket for wards, they're all on CD and you can't place a new one. The enemy jungler comes and takes red buff, then ganks your lane and takes turret.
Let's look at one more possibly scenario: Your team is trying to sneak baron, but the enemy has it warded. You have a yellow trinket because you didn't want to buy a sight stone, so you can't clear it with your red trinket. The enemy team's support uses their red trinket to disable any wards you have outside of the baron pit, and the enemy jungler knows exactly when to jump in for the steal. You lose baron, and they ace your team, then push to end.
You're only hurting your team by not buying a sightstone. Vision is important.
