The NFL draft is about more than just selecting players to fill positional needs.
Teams can use it to manipulate the salary cap by getting value through set rookie wages. It can give squads a chance to target position groups they cannot in free agency or to build a surplus of talent at a position to prepare for expiring contracts. No two teams' needs are perfectly comparable, nor are the ways in which they can approach them.
For instance, one team may prioritize drafting cornerbacks because it needs new talent on the field right away.