What if you don't want the same applications with the same interface modalities on different devices? Shouldn't we be much more concerned about data portability than application portability?
In an ideal world, you'd be able to choose from a variety of programs, to optimize for your usecase, all while maintaining data portability/sync.
Convergence is a practical choice to allow contributions to be shared by desktop and phone users.
https://amosbbatto.wordpress.com/2020/08/05/advantages-of-ph... discusses this.
If you use the same app on your phone and computer the data is almost certainly portable between them.