Earlier quoted context omitted.
This is imo how most people should start and use it. All these "structure first" approaches are like using someone else's preferred way of learning and memorizing, if it works its an happy accident. You'll get your structure out of your mind once you learn to know it.
I am constantly finding myself deliberating whether I should or shouldn't use folders in my Obsidian vault. Most of the times folders feel artificial. I prefer tags nowadays as the single source. The times I separate to a folder is for very-specific Dataview data-only pages, and for storing assets such as images.
Tags I barely use, except for things I can't put into "atomic notes". Like when someone mentions a book and 1-3 sentence review, I add it to today's diary entry and use #book tag on it.