The champions or the playstyle of supporting and having to function with less XP and gold.
I say the latter because many support champions like 
aren't mechanically hard but having to function properly at a level and gold deficit along with literally relying on your team for damage most of the time is the hard part.
Best Kog NA3 votesI have to say dealing with the fact that you're basically going to be blamed for anything that goes wrong because you are support. (This is coming from an ex. support main)
OneMustFall2 votesI don't know what you're talking bout. Support is the easiest role in the game.
Marshbouy1 votesI am quietly agreeing but i can't say that without getting burned at the stake. BTW, even an easy role still has a modicum of difficulty.
Resonance x LFT2 votesYou can't control your teammates actions.
Environmentalist1 votesThis x 4957838472 ^ Supporting friends when you're on voice chat together makes it soooo much easier, but hoping that the random silver 4 Vayne you're supporting will listen to your pings isn't a great strategy when you're hoping to engage or disengage.
Big Lincoln2 votessupport is easy as fuck, dude
if supports were actually fun more of them would get picked, but all you have for fun is Bard and he's notorious for ruining teams with a bad ult (even some hundred of games playing him since release, I'm guilty of it occasionally)
the problem is that most of them occupy either the same role or they do everything. there's no unique niche for them to fill because most of them are designed around sucking their team off instead of doing anything interesting on their own. It's all CC spam and heals or shields, no buffs or debuffs and auras have pretty much all been removed, only a few offer any damage on their own and none of them apply it in interesting ways besides AA enhancements
Hethalean1 votesIdk there is an aspect of your level of contribution and the window upon which you can give it before you die. Being behind in gold and XP means you lack some level of tankiness (so mages and assassins get not really free gold, but easier gold on you) due to gold and levels (HP / level, armor / lvl) and damage for the same reasons. Idk. mechanically, support isn't TOO hard. however, there are aspects about it that give it difficulty. Is it the hardest role? idk. I'm a support main, but I sweat bullets if I EVER somehow get mid.
Zach Sandwhich1 votesI feel like the problem with Support is just the nature of the role.
As a support your job is, well, to support.
If your team is going full ape mode theres nothing really there to support...
DemonBoneJangles1 votesyes this is true, when you "the support" are supposed to happily trudge along with your squad of rampaging primates only to be the first one dead because... oh wait we were so busy chasing the enemy "TANK" that we didn't notice the other four enemies close in on us because, "hey your the support you need wards down" but yet everyone is sitting on full charges of their still unused friggin trinkets
Zach Sandwhich1 votes[{quoted}](name=Requiem of Bones,realm=NA,application-id=3ErqAdtq,discussion-id=Bfkycwx5,comment-id=00030000,timestamp=2016-10-30T22:34:19.097+0000)
yes this is true, when you "the support" are supposed to happily trudge along with your squad of rampaging primates only to be the first one dead because... oh wait we were so busy chasing the enemy "TANK" that we didn't notice the other four enemies close in on us because, "hey your the support you need wards down" but yet everyone is sitting on full charges of their still unused friggin trinkets
Trust me dude, i'm a support main. I understand that feeling ALL too well.
DemonBoneJangles1 votesSupport and jungle main myself my friend, the feeling of pain is real for the supports
Brighton1 votesProbably the play style. Let's be real, in your typical solo queue game what is the point of building "supportive" items like locket or Crucible on Karma when your "damage" dealers aren't going to be good enough to output damage either way.
Sasogwa1 votesWell it's the whole point of this class of champions. Their have kits have high utility and bad scalings in general, or high base damage. That's basically why they are great at the support role. The entire purpose of the botlane is to mix a champion with extreme synergy with items and less reliant on level like sololaners, so the adc ; and a champion that FUNCTIONS without needing items, and even levels are not essential.
Why would we then consider those champions to be difficult because they have less resources? That's their trademark, basically. It's like saying a melee kiteable champion is hard because he gets kited, or marksman is hard because you are squishy.
Deal with it, play on your strengths, understand your weaknesses. You won't brute force carry with stats and farm, like you could with someone like 
for instance.
However, you will carry through laning phase, by setting up right trades ; with your vision control ; with your calls ; with your way to play the teamfights.
It's hard to solocarry as a support if your team is worthless, that's true. Teammates don't follow calls, people are feeding because X reason, etc. shit happens.
But still I think there's a HUGE deal you can do. Like, really.
I think people are sometimes less interested in support because it feels less good. Like, it feels good to deal damage I guess.
Though you can always go for 
