Even at 1700+ LOTS of people cant buy wards without me yelling at them.
Its how i got to almost 1800 PSR. I pick a support hero, babysit the carry, keep wards up the whole game (also counter wards) and not stealing farm from people who need it more.
Your job as support is to harass the opponents and give most of the lasthits away to the one you are laning with (if he needs them more than you do, which is almost always the case). You are also supposed to upgrade the courier ASAP. You need to put up atleast one ward at 6:00 to see the rune, and from that on, you shall get wards when possible. I dont care if you want your ghostmarchers, wards is a must!