The resemblance between Fifth Age sorcerers and 3E+ D&D sorcerers is primarily in the name. 5A sorcery was still a learned and intellectually-based (Reason, under the SAGA rules) ability, limited in what it could control and effect, but capable of being shaped in the casting within the schools the sorcerer knew. It doesn't much resemble the inborn, Charisma-based, 'pick from the same spell list and cast in the same way as the wizard' of 3.5, but the name similarity, the interests of compatibility, and other factors squeezed the round peg into the square hole.