I totally disagree. There is a huge difference in the amount of effort required to pedal an IGH up a relatively steep hill when compared to a derailleur bike. I have an IGH bike, so I would know. People on derailleur bikes fly past me on uphill stretches.

The Gazelle Friik you link to is very interesting. It is indeed a derailleur bike with a full chain case. However, it only has one chain ring in the front, so the range of gears is limited. This matters, particularly for steep uphill stretches. Still, nice to see. However, the comments in the youtube video indicate that it was a short-lived bike and is no longer in production. SMH.