That's a dotfile...
It’s much cleaner and it comes with a more logical and useful split of config and cache stuff, e.g. you can just skip .cache when rsync-ing to a remote storage instead of having a long list of per-app escapes…
As I don't usually remove programs (or install new ones, for that matter) the scheme that works best for me and many others is "storage/app". In an ideal world a hybrid scheme might be possible, but as it stands now it is not an option and one way has to be chosen over the other.