Are tags practical ? Sure Tags VS Folders have Tags with all the advantages.

however will most normal people have the time to refactor the tags ? Or will their tag system become a mess.

Lets take Ash and Ash and Ash.
How will you tag a picture ?
https://en.wikipedia.org/wiki/Ash_Williams
https://en.wikipedia.org/wiki/Ash_Ketchum
https://en.wikipedia.org/wiki/Ash

And you need to really really really be precise with the tagging system. Either you start with a tag that is something like this

fiction/franchises/Pokemon/Ash
and
fiction/franchises/Evil Dead/Ash
Reality/Ash

Or you will need to refactor your tags later. And you better hope that you did not introduce a problem like tagging Ash_Williams as Ash forgetting about it and then collecting Ash_Ketchum pictures and tagging them Ash

Now you must by hand sort these files and retag since this will be a one to many operation on the tags.

The nightmarish mix of tags you can get a impression for is by looking at AO3 and their tags.

And this is the easy stuff. Franchises must have different names (or lawsuits) and in them they have encapsulated names.

However reality is far more messy, what about celebrities there are multiple people with the same first and last name. How will you tag this ? What about MEMEs ? This is a serious question. When memes show up they do not often have a official name so people give them whatever names will you later be able to remember that this and refactor to whatever the KYM name is ?

Will tags not create a even bigger mess then simply using folders ? How will you refactor your tags and retag if needed ? Will the long names needed not make people lazy and tag their files incorrectly or not at all ? Making a tagging system basically a black hole.

This ignores that the tagging system will need to have advanced features from the start.

>registered tag database (no duplicates)
>refactoring tag commands
>Multi tagging and retagging by hand