Tags are less structured than folders, but more structured than natural forming links. Tags are great when you searching with an intent to find notes for a genre or general topic across all folders and links.
Some of the tags here have index notes like this one associated with them for improved navigation, but a lot of the tags are junk or have a very specific scope. They will be updated slowly but surely.
A lot of tags also have subtags. My note-taking app treats tags like folders in that tags can have parents and children (computer science terminology). For example, you can have a tag #pets/cats/Oreo, where Oreo is a cat, but ALSO a pet.
For Thought/Zettelkasten notes, I used the seed —> sapling —> tree method, see their respective notes.
For my Academic Writing notes and study (although more general purpose), I use mostly todo —> working —> none, to help me manage working priority.