I think part of the issue is that people are accustomed to support champions having strong peel, CC, or poke and expect the same when playing Taric. Personally, I find that once Taric gets a couple items into his build (i.e. Iceborn Gauntlet) he can play as a bruiser reasonably well while providing buffs to his team, but he's not as strong as other supports at initiating or peeling. Instead of providing CC to help his team, he acts as a beefy wall whose damage cannot be ignored for a prolonged period of time. After you get some CDR, you can pretty much indefinitely keep an ability off cooldown and cast it as long as you have mana.
And his early game isn't horribly weak. He isn't really great at setting up early plays against the enemy bot lane, but he's pretty good at punishing/discouraging aggression and sustaining himself and his ally. It can be a bit troublesome against poke comps, but it's not bad against champions who need to engage on you or your ADC.
As a support, I typically get:
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