You are confusing narrative and character development.This for me encapsulates what I hated about 1e magic items & which has been carried into 5e that is GMs having more say in character development than that characters player.
Narrative is what happens to the character.
Character development is how the character reacts to those events, by learning and growing, by becoming bitter and mean, by remaining static, etc.
The discovery of magic items is generally a part of the narrative, which is the purview of the DM.
If your DM allows the creation of magic items, it then becomes part of character development.
Since both options are available, you cannot say 5e is strictly one or the other. If you are playing with a DM who doesn't use options you like, either talk to him/her about it or find a new DM.