This has probably been asked before, but...

I recently started watching David Marks on DIY. I have yet to see him cut a
"real" tenon. Always loose tenons using a multi router.

Why is this? Is there an advantage to loose tenons that I am unaware of?
Does he just like to show off his multi router? Are they just easier to
make?

I use to only watch Nahmmy and I have learned 90% of what I know from him.
Nahmmy "rarely" made loose tenons.

Confused...