While I agree with the general sentiment that the mental model of tags is more complex and discovering the right tags is a bigger challange than slapping some tag onto some file, I don't see it as something that needs to replace a traditional file system.
Tags are more useful for certain types of files than others. E.g. let's say you want to mark certain projects done. Instead of moving them to a done folder you can just add tags to them – without changing any paths you change their status.
Tags are also quite useful for pictures, music and other media content.
I never really got, why even in 2019 there is not good support for tags on most desktops.
Windows has had file tagging since at least XP. Not a lot of people use them (probably because the UI for it is hard to discover), but I have used stuff like royalty-free photo libraries that have searchable tags.
Moving and duplicating both preserve the tags: they're metadata. They're part of the reason for those pesky .DS_Store files that proliferate on network shares and non-Mac filesystems, in fact.
Tags are more useful for certain types of files than others. E.g. let's say you want to mark certain projects done. Instead of moving them to a done folder you can just add tags to them – without changing any paths you change their status.
Tags are also quite useful for pictures, music and other media content.
I never really got, why even in 2019 there is not good support for tags on most desktops.