I don't think describing Hetzner as IaaS is very accurate. They do offer that as well, but also dedicated servers, VPS and more.

Personally I use Hetzner exclusively for their cheap and unmetered dedicated servers, as I don't like paying per GB used or similar, I want one static cost per month regardless of anything.

In fact, when I think about it, most other Hetzner users I've met have similar objectives and I don't think I've met anyone around me in real-life that was using the IaaS part of Hetzner.