What is Lee Sin's Win Rate, and how many people QQ about him being OP?
At 50 games or above, 49%. I'm not complaining about Lee Sin.
This proves nothing. Just because people sometimes complain about champions incorrectly doesn't mean they do it all the time. I can cite examples too. People complained that Veigar and Kassadin were going to be too weak after their changes, and they were right. This kind of discussion means nothing.
I would say that most supports can be useless in teamfights, just they contribute dmg, so even if they don't use thier skills optimally, they will still have an effect.
I disagree. I play supports specifically because they can impact teamfights massively. Bard has a unique uselessness in teamfights. 2 of his abilities can have absolutely no impact if a teamfight doesn't start on his terms, and the ultimate can also have a very low impact. The heal shrines are weak in the late game even under ideal conditions, but if he doesn't stack them up before a fight starts, they do almost nothing. Depending on where an engagement happens, the magical journey can also contribute nothing to a fight. The ultimate can be useful, but if an enemy has already engaged in a successful position, using it to effectively prevent losses without also screwing teammates can be next to impossible. I would take literally any support in a teamfight over Bard.
Bard doesn't have that, but he makes up for it by have WAAAAAAAAAAAY more utility than other supports.
No, he has different utility, and the usefulness it has is much more situational.
If your team is any good at rotations, vision control, and minion waves control you can out meneuver the enemy team, pick off some key members and take some objectives.
I can do that with other supports too. A Blitz or Thresh hook or a Leona ult can make picks very easily, and they don't risk uselessness during teamfights. Bard offers a few more options for the team rotations, but they can't make up for his weaknesses. I'd much rather have Leona roaming with me than have Bard roaming with me.
This would be much more true if Bard wasn't so undertuned. His numbers are just too low. He could work in theory, but right now, he's just too weak.
Is it Bards fault when the team doesn't follow up properly, or the ADC doesn't pick up his health shrines in lane?
Two things. First, I don't see this happen anymore. If I lay a heal shrine, it gets picked up once it powers up. If I ult someone, the team will engage. I think he's bad despite that. Understand that when I'm saying that Bard is bad, it's not because he's being played with people who don't know that the champion's abilities do.
Second, it is Bard's fault that he has a minimal teamfight contribution outside of the ultimate. It is also Bard's fault that even with the healing shrines he offers very little in lane. His Q is decent, but his meep damage is very easily punished because of his 500 range. He's extremely easy to trade against, and if he starts losing even a little, bullying his carry becomes stupidly easy, particularly since you're guaranteed full-exp denying potential if he ever roams at that point.
I feel like people perceive Bard to be bad, so they do things to confirm this in game (either subconsciously or consciously).
I do not accept this as being a major reason for his current lack of success. Numerically, he's undertuned.