Good question ian!
1. It looks cooler
2. It taught me a different way of doin things with the cnc router
3. It ensures there are no misalignment issues compared to a 2 piece setup
4. Its less material sizes to keep hold of
5. Less parts count
and lastly, its only 10-12 minutes per spoiler panel to cut them out like this.
Overall, it would be quicker and easier to do multi part spoiler panels, i just like to do things slightly more difficult. Lol