I think you miss the point of the cloud. It's not supposed to be cheaper. If you want cheap, yeah, run on Hetzner. If you want to deploy a WAF with complex rules to route specific traffic to either a multi-region ALB or a bucket with a WAF built in, and do it in 10 minutes, you use the cloud.
Why do you care whether it "needs" to be done a certain way? You could use Hetzner, or you could use some giant cloud infra. Both get the job done. Why do you care which is used?
You probably care because you don't like waste. But another person might not care so much about waste, and cares more about other things. Like the time it takes to get something done, or the technical ability required, or the ability to find someone else to maintain something, or its flexibility in being changed. Or maybe just the fun of building something with cool toys.
You originally commented with cost being the factor. But if the person building this doesn't mind an additional cost, then they don't need to build it on DO or Hetzner. That said, if they do built it on the cloud, they do need to keep in mind the cost... just like if they built it on DO or Hetzner, they would need to keep in mind how to rebuild the instance when it goes down, how to maintain the instance's OS for security patches, etc.
Both require additional considerations besides the one thing. Your choices just move around the necessary complexity.
I generally care about unneeded complexity mainly because often times when you switch projects you inherent a ton of it. Also many projects don't see the light of day because people overcomplicated the infra too much.
