First off...Not many people want to support to begin with. I mean what glory is there in supporting a team? You rarely get kills, but get a lot of assists if you are good. In this game everyone prides themselves on how many kills they can get, and the more you have the better the LOL player you are. So because of this no one wants to be that guy with a zero in kill score. And even if you pull off great assists no one thanx the support for their help.
Another reason why it's hard to find supports...adcs tend to be jerks. Most are cocky, and think if it were not for them your team would not be winning. These guys are the A holes of the team. Let's admit that as a support it gets old listening to the adc pat himself on the back and then complain if the support accidentily gets some cs or the adc misses the cs and then yells at the support anyway like it was their fault. So next time you are waiting a really long time for support and all you get are adc's entering under support remember be nice to the next real support you get. They are a person too, and they are the key to victory along with the rest of your team. And if you see your adc being toxic to a support report them. Then maybe more people will play that role.