She is in fact bad but she isn't horrible so people still defend her position as a support. Her poke isn't better than other mages that go bot like vel'koz,her tether basically never goes off,she doesn't have hard CC so she can't deal with an assassin jumping on your adc as well as others,her shield only lasts 4 seconds and just a small speed boost,the shield changes they're making aren't even good with the final numbers,yes they're loweringmana and cooldown (at later levels) but her shield is so undertuned when you compare it to every other supports shield.
Her passive is bs that should be on her ult when Lux and Lulu have damage passives
So really her strengths aren't really what makes her good isn't something a champ can do better.
Her poke doesn't go past minions and her R+Q basically never goes off both times on a target.
Her tether is the worst in the game and basically never snares OR if you are in range to snare you're usually taking too much damage
Her shield is so mediocre when you compare it to Lulus when it lasts 2 seconds longer, gives your adc magic damage,and has a damage option that gives vision.
R+Q is strong but rarely does full damage
R+W is a good heal but it does that cause it doesn't do something useful like stun,knock up,polymorph.
R+E is just a bad version of actives other supports buy along with their innate hard cc.
