EFL is optional. You can utilize other APIs. QT, Clutter, or GTK etc. can probably be used it's just that the Tizen developers didn't put the effort to add it. Tizen being a full GNU Linux system with Wayland can utilize any APIs that Wayland has access to. To my knowledge there is a community qt port to Tizen. Most likely the application would just bundle the libraries and share them with other applications that use w particular library