Chrome has google accounts to synchronise recently viewed pages across devices. This is just Mozilla's response. There is already a popular extension, so why re-invent the wheel?
Firefox already has sync built-in. I think this is supposed to be an improvement over the current bookmarks system. Mozilla realized that Pocket was already doing that better than they were, so they just integrated it instead of reinventing it poorly.
> I think this is supposed to be an improvement over the current bookmarks system.
The old secure Sync was great, absolutely great. I could see all of my bookmarks and history from all of my machines, and it was all well-secured. There was nothing wrong with it.
I see this as Mozilla basically admitting that the extension model has failed; this is a textbook example of an extension, but they've decided that's not good enough.