Remember files? A lot of awesome stuff existed thanks to files being the atom of computation, but it's all somewhat disappeared of late
So much work on desktops resolves around files. Your desktop has a bunch of files, and you use programs to work on them. So you have your spreadsheets, images, and other goodies. And you have your tools to operate on them.
so you work off your files. They're pretty portable on account of being files, and other people can write tools to work on them. So people can write save file editors, data browsers, or even full-fledged clones of other apps.
But then Photoshop has access to your
.bashrc. The permission model, in practice, is "everything can be touched by anything". Which is less fun when devices start having GPSes.
So most mobile OSes, realizing that people like security, went to a different model. Each app has its own data stores, and other apps can't go getting into it.
This new security model is kinda awesome! Your programs work in a mostly isolated environment, so things tend to work by default.
But now when I'm using an application on my phone, by default none of the data is available for transportation. Sure, a lot of bigger apps have Dropbox, but most don't.
That awesome recipe app with 1000 users but no updates in the past year. It might be storing things in a simple SQLite database, but it doesn't matter because nothing else will be able to get to the information.
It's harder to get Libre Office in the universe of mobile apps.
A tool-oriented OS is one operating on objects, more than one based in applications(Places). I hope the next generation of OSes will be able to come back to exposing data to the users, instead of sandboxing it along with the apps.