Whether jungle or top lane this champs only problems really seem to be mana. I've played it and played against it and you pretty much just dump two points into your heal and maybe max E first. The two points is enough to get two stacks back everytime you use it and you have a permanent passive and constant heals as long as you have mana. Champ is legit unduelable as a melee and you still have utility for your team to boot.
Same reason why Poppy isn't doing good. He has no engage.
If we're talking juggernauts / fighters. They got the damage to kill the enemy and damage win games / mobility to catch the enemy. Taric goes more into tank but does he have engage? Nope.
Taric CAN win games but you gotta rely on someone else to engage which is not something you want from top lane. Unless you got some engage somewhere else.
Like I've had many games where I beat my lane opponent but what can I do with my lead? I can beat anyone if they get close to me but I'm NEVER gonna be able to catch someone. And if my lane opponent is smart they'll just walk away from me after they realize that Taric top isn't a joke.
Idk either his passive is great especially with a triforce and hydra, it's probably cause people can't think of a "support" being in a solo lane or jungle even tho he can jg better then others jg's
because taric is pretty good with 
which means he is an amazing support. I'm not opposed to taric top, but id rather him be my support
Not only mana, vs decen opponents his lack of mobillity and reliabillity also is an issue. Any somewhat mobile chamo can easily avoid the stun and prevent him from chaining his spells+passive by not stayin in melee range. and frankly, hi contribution to teamfights as sololaner is hardly different than that as suport
Waveclear and itemization.
Taric currently is extremely good when you abuse ardent on him, and that is not an item you can build in lane.
RoA alternatively would be a better option since it gives hp and ap which makes your heal better, but that still doesn't fix the waveclear issue.
If you build ad, then you aren't getting stats that benefit any abilities in your kit.
If you get Sunfire cape then you have the waveclear and dueling potential, but at that point you might as well be playing support considering there are champions with that amount of waveclear in their kits already. ( this arguement doesn't work for shen since his ULT lets him teleport around the map, thus making it reasonable that he is in another lane dealing with minions while building waveclear )
If you are alone you are only using half of your kit. Since you bind a teammate, you can double the amount of abilities cast to cover a greater area. It just isn't efficient to stick to a solo lane when your entire kit revolves around binding to a teammate.
But hey, do what works for you
