Nerfed Items Are still used by champions that work with them.

Im going to focus on sejuani here with this discussion. She got nerfed due to her being to strong with cinderhulk, and cinderhulk was nerfed. That wont solve the whole problem however, as Sejuani still builds Cinderhulk so she still has the synergy with it. If they Just nerfed Cinderhulk Sejuani still would have been strong, as the items that made her op were still around, albeit weaker. Tldr: Nerfed Items are Still built on champs.