Only for large scale multiple user applications. It’s more than reasonable as a data store in local applications or at smaller scales where having the application and data layer on the same machine are acceptable.
If you’re at a point where the application needs to talk over a network to your database then that’s a reasonable heuristic that you should use a different DB. I personally wouldn’t trust my data to NFS.
This, though I think other posters have pointed to a web app/site that’s backed by SQLite. It can be a perfectly reasonable approach, I think, as the application is the web server and it likely accesses SQLite on the same machine.
If you’re at a point where the application needs to talk over a network to your database then that’s a reasonable heuristic that you should use a different DB. I personally wouldn’t trust my data to NFS.