Gnar wasn't even buffed in a numbers sense. He was giving QoL improvements because his boomerang would randomly fly off in a different direction.
That being said, he had a few tweaks a few patches later on nerfing his mini gnar Q but buffing his mega gnar Q yet reducing the ad scaling. But mostly it was the QoL change that helped him the most. A champion shouldn't rely on whether or not his ability decides to work correctly or not or however buggy it feels like being at the time.
Anyways on to the topic: Bard I think does need a buff because chimes aren't rewarding. People just pick them up but do they think about why? They scale really slow and by the time you have 80 or something the base damage from a meep is negligible because everyone has armor/mr/health by then. The slow is pretty nice but doesn't feel impactful during teamfights. His shrines to me are just a speed boost since the healing is minimal from mid to late game. His ult is more useful as a catching/running tool than a teamfight tool. His E is fun but easily telegraphed plus enemies travel through it faster in my mind than they should. His Q is incredibly short ranged, slow missile speed, puts Bard in a risky position to get harassed. He's really too squishy to be using such a short ranged skill.