Let me pull from my experience as both support and jungler...
Of all my games, I rarely if ever see people upgrade their green trinket. That's 250 gold. Yet they want the one person on the entire team without a good amount of gold income to spend 800 gold on 150 health and 3 wards every recall. Yes, it's nice, and theoretically a support can recall multiple times to light up the minimap like the Space Needle on New Year's Eve. But here's some math:
Nobody buys a ward or upgrades their trinket + support buys sightstone = approximately 8 wards max from a single recall
or
Everybody upgrades their trinket + support doesn't buy sightstone = 10 wards max, plus support is more durable (seriously, let them buy a chalice or something. 150 health is what, one spell and/or autoattack mid-game?)
Now, you're complaining about supports not buying sightstone, so I'm allowed to complain about teammates not upgrading their trinket. But let's consider other possibilities.
Everybody upgrades their trinket + support gets sightstone + support switches to sweeper lens = 11 wards before recall + minor vision denial
But let's get a little deeper, shall we?
Everybody upgrades their trinket + support gets sightstone + jungler gets sightstone = 16 wards max, or less (12-14) if support/jungler gets sweeper lens for moderate vision denial
Everybody upgrades their trinket + support gets sightstone + everybody (except support) buys at least one ward per recall (seriously, it's like three minions. One fourth of a longsword will not lead to #LCSBIGPLAYS) = 17 wards, or 20 if the jungler also get a sightstone
I don't know if you're getting my point yet, but the sightstone should not be mandatory, but an optional possible strategy for the entire team when it comes to vision. There's many ways to go about vision and vision denial, but you should NOT be harping on the support if the entire team's vision is suffering. If the people who actually get to farm and cs can't spend 250 gold to have viable vision plus the occasional ward/pink, then you should be able to see why I consider it a bit audacious to ask the 0 cs support to spend 800 gold when he/she can be buying some defenses/mana so they don't get blown up.
For example, let's look at bot lane. A support typically rushes sightstone and switches to sweeper lens, while the adc almost never upgrades that trinket. That's four wards and one vision denial. Taking that into account, where do you ward in bot lane? Tribush, river, maybe the two bushes (or save two wards when the first two run out). That's FOUR PLACES TO WARD, which is covered by sightstone + adc trinket. But you know what? If both laners upgrade their trinket, that's FOUR WARDS and 500 team gold spent, AND the support can grab a little defense with the profit. You sacrifice a bit of vision denial with that strategy, but sometimes the team needs to sacrifice something for the support rather than take without giving.
My word isn't law, nor should it be taken too seriously, but it's just a little food for thought. People thrust the warding role onto the support, when it can easily be equally shared between the entire team. And no, I don't buy that it's the support's job (as in, part of the role alongside the team's warding), I find it to be an excuse for people to hoard gold. Yes, I've played adc/top/mid before and I've almost always had a little pocket money enough to buy a ward or even upgrade my trinket, so don't even try. Yes, there are exceptions and you can't always buy a ward, but it's always good. A ward is ALWAYS good.
And of course, you get junglers like me who hit tab, see who didn't upgrade their trinket or buy a ward, and then proceed to camp that lane.
and she said "I already have greater stealth -.-"
