I just encountered a Platinum support main refusing to buy Sightstone + taking CS from the ADC
Looking at their match history, this player is consistently behaving like this, and it's pretty clear that they're trolling because it's the end of the season. My guess is that they realized they couldn't reach Diamond, so it's now fucking around in all of it's games.
They aren't intentionally feeding, but their behavior is intentionally making it extremely hard for their team mates to win. This really is not okay.
Can something please be changed to hold players to some standard in ranked games? Playing support and not building a Sightstone or buying any wards is understandable if they don't know better, and is even probably okay in normals, but this player clearly knows better.