Support main here as well; I'll drop some insight on vision, and Sightstone vs Upgraded Warding Trinket for supports.
This'll be a long read, but it'll also explain why Sightstone is still the norm for a support. It's a hefty read, so I'll try to format it to be less of a monolith.
- Why isn't vision covering my lane from ganks enough?
Warding also isn't just to prevent ganking of one's own lane, but includes (and is not limited to) reducing the ganking of other lanes by pointing out the enemy jungler, allowing your team to make plays without repercussions, and enabling the aggression of another lane because they know where the enemy jungler is. In addition, if your jungler is a duelist/counterjungler, knowing the enemy jungler's location allows him to move accordingly to counter the enemy jungler's efforts. That's how important the vision game is; you never want to truly lose the vision game, otherwise you risk losing the whole game itself.
The earlier you can get a wide field of vision, the better it is for everyone on the team.
- Why aren't my laners upgrading their trinkets? What if everyone just upgraded their trinkets?
For a laner, the 250 upgrade on the trinket is an investment that pays off later, so it's a purchase that one gets when one is winning and can afford to drop gold into more vision to snowball even harder. Trinkets also cannot be upgraded until level 9; and most laners cannot buy their trinkets until a little after, because they don't want to fall behind in item building vs their opposite laner otherwise the extra vision would become a moot point. The support is also delayed from level 9 because of the shared lane xp and because roaming to ward delays leveling slightly.
Thus, earlygame, the only vision that is granted is from trinkets; and that vision lasts only a small duration. Early-mid game, the only vision that is granted is from the support's sightstone if they choose to buy it, other peoples' trinkets, and any bought wards. If you neglect to purchase a sightstone early, then your team plays blind until midgame (at which point, it may become too late to recover from the advantage the enemy team gained from your own team's lack of vision, etc).
- What if everyone makes it to midgame alright, and I have the option now of buying Sightstone vs Upgraded Warding Trinket?
Midgame, however, becomes tricky as well because the enemy support will be actively sweeping wards out (and you should actively do the same to him). With only an upgraded trinket, you're only able to plop 1 ward every 60 seconds; if the enemy team sweeps out even a single ward, they've created a huge gap in your vision that can be exploited. If you have a sightstone, you can quickly fill those gaps
In addition, any support who purchases a warding trinket has a reduced capacity to ward sweep, which is crucial for any support that likes to carry (which sounds funny, because you'd never expect a support to carry). By sweeping out wards with a sweeper in addition to pinking areas, you cause the enemy team to play more blindly. And as we all know, playing blind is a huge disadvantage; you're crippling their whole team with one item! But if you upgrade your trinket to a warding trinket, you have no sweeper!
Supports carry by denying vision; by not purchasing a sweeper, you're reduced to becoming just a warding cc-factory because support damage falls off mid-lategame without Void Staff. If you intend to do huge damage as your ADC's partner, then you've essentially become a kill lane duo; in which case, you should state that in champion select so your team can adjust accordingly. Your team can then play around the fact that you're playing as a damage champion, and not necessarily a peeler for your ADC (whose role it was to deal damage anyway), or as a primary warder.
- Why should I be the one shouldering warding costs?
Whoever deals damage (whether it be APC or ADC) scales exponentially with itemage. This means that an ADC with 6 items is better than one with 5 items; but the gap between 5 items and 6 is much larger than the gap from 1 items to 2 items. This is usually seen when an ADC purchases their PD/Shiv after their IE and their sustained DPS increases dramatically, or when they purchase Voidstaff or Last Whisper, and gain huge penetration.
Because of this, it's beneficial to grant as much money advantage to your ADC (and APC) as reasonably possible; this means that to an extent, becoming the main (but not sole) warder for your team early-mid game. Once your team is snowballing, your laners can purchase extra vision to snowball even harder; but until then, it's more generally more efficient to have specialized roles of dealing damage, tanking, warding, etc.
I'd also have to say that an early sightstone also helps your team snowball, which enables your team to then purchase warding trinkets. The vision you grant allows your team to purchase the vision that complements your initial vision.
- Am I wrong for asking my team to complement my vision? Is that Ezreal in the wrong?
Nope; your team should indeed be trying to complement your vision. As long as you have some vision placed, you enable your team to safely place more vision. The circumstances would have been a better determination on whether or not Ezreal should have upgraded his vision, because most ADCs (especially low mobiilty ADCs) aren't good at warding; if they get caught out, they're dead as doornails. However, I do agree that he shouldn't have been facechecking bushes; he has abilities that can spot for enemies in bushes, silly him!
TLDR: Too bad. The above has juicy information that can't be summed up any shorter without making it seem out of context. If you can't spend 10 minutes to read to improve your game, then no amount of TLDRs will help :D
. When a premade on my team found out I was promptly flamed and blamed for us losing the game. You see, generally I don't buy a 
and
. Later on in the game I upgraded my 
and kept up with the pink wards I needed to get vision on key locations. A few minutes later our 
, the main rager, cried passive aggressively about not having vision when he face checked bushes in our jungle, to which I told him if he upgrades his trinket he could help me ward since I refuse to get sight stone 30 mins into the game. He never upgraded his trinket.
support or something ridiculous.
