I am not the author of the previous comment so my view could be different. But I have thought about it. With tags, you could have got one note in multiple directories. Imagine I have found an interesting blog post on HN about SQLite in python. It could be problematic to decide is it more about python of Sqlite? Tags could look like this:

python, databases, SQL, SQLite, $date, FromHN, beautiful_site (I liked the look of this blog)

or in proposed system

/IT/Databases/SQL/Sqlite /IT/Python/libraries/SQLite /IntrestingHNposts/2022/July /beutiful_site

the difference between "just folders" and the proposed system is that you could have one note in multiple folders. Which gives you more flexibility in assigning notes to its topics. But it is still more structural than tags which could easily turn into an unpenetrable list of random words.

To be fair you could also achieve it with symlinks.

As a node in a tree hierarchy any folder can only have one parent folder. Tags of course allow nodes to have any number of parents (aka "associations").

The relationship between arbitrary nodes in a tree can be determined by tracing their common ancestry, but tags don't provide equivalent functionality, unless you strictly define how tags themselves relate to other tags. An obvious way to do so is to prescribe that every tag shall have exactly one parent (except for the root abstract "thing" tag).

In other words tags become folders, but any non-folder content of those folders can simultaneously live inside any number of folders. Similar to symlinks, but arguably less hacky, because there is no differentiation between "actual" location and "linked" location.