You can copy/paste the notes to actual samples. Plus when a MIDI is imported, it displays the accurate bpm of the song and if it uses panning, pitch... whatever, those properties will be available in the file as well.
Some users do use midi files to make collabs. For instance, a person does an arrangement in FL and export it to MIDI. Then He/She will send it to another individual, who will import the MIDI and replace instruments to improve production, or add arrangement parts...anything. Imagination is infinite.