Annie's strengths are that she can AoE engage a high damage combo onto squishies.
Her stun duration was nerfed a long while back to scale back to what it was eventually.
Her weaknesses are that she has a limited range, and her hard engage is flash dependent.
This mean's poke is best against her, and having a strong front line that she can't walk up towards.
Part of the problem is that strong front lines have fallen out of favor, only a few tanks are played such as Maokai and Gnar. So having a consistently strong front-line is rare. Poke is very vulnerable to being engaged upon, as it tends to lack disengage (Xerath, Jayce) and be squishy. This means when Annie has her Shurelia's/Righteous Glory as well as Flash, she can engage almost whenever she wants onto them. Top that off with one of the strongest laning phases of supports, and you have Annie.
Death is the strongest CC, and Annie often kills people with her base values herself.