This app (widget) vs platform battle has been played out many times before, with different outcomes.
1. apps on operating-systems (windows) - the widgets lost
2. browsers on OS (windows) - the browsers initially lost, then have recovered to make it a tie.
3. websites on browsers (IE) - the widgets won.
4. apps on featurephones (telcos) - the widgets lost
4. widgets on websites (FB) - the widgets lost.
5. Apps on phones - still playing out.
6. enterprise widgets on enterprise apps - just starting out.
Typically, the platform consolidates and the widgets lose. The winning platform owner likes to have a widget economy to enliven up the platform, but doesn't want the user-to-widget relationship to get too deep. In particular user-identity, monetization and terms-of-user are the gateways through which the platform owner keeps the widgets under control.
Widgets can win if there is platform diversity and competition. Unfortunately, in the last 6 years, Facebook has gobbled up the collective online attention of the human race. The consolidation of the web into one widget platform meant that consumer widgets had to establish a direct relationship with the user through Facebook - a hard proposition given how Facebook's communication channels works. If Myspace, hi5, G+, Ning or anyone else had succeeded the story may well have turned out differently.