Dropbox is a great example. It's now a fundamentally different product than the original, and has re-created exactly the problem the original solved. There's no

Dropbox is a great example. It's now a fundamentally different product than the original, and has re-created exactly the problem the original solved. There's no longer a good cloud-synced folder tool; everybody has gone back to implementing network filesystems that are much more complex and a badly leaky abstraction.