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I use it a lot for file uploads in web browser.

A good (only?) workaround is using alt tab but if you have many open programs it can be quite annoying.

It used to not work for the longest time because Apple used to have a patent for it, which I presume expired.

I use it daily for copying files, since you can effectively select a window from behind other windows just by hovering over the task bar icon. It's gonna suck having to rearrange windows before this otherwise simple task can be completed.