Does annie outscale other mids and supports?
People with mobility like ahri or kalista (not mid or support but) will be countered especially in a teamfight. Annie will do a crapload of damage. Maybe disadvantage is not tanky but if you build roa/rylais maybe side tanky? Idk. For me one aoe flash stun tibbur 3 people (Realistic) will end the game mid/end game