Anyone who thinks DO and Hetzner dedicated servers are fungible products is making a mistake. These aren't the same service at all. There are savings to be had but this isn't a direct "unplug DO, plug in Hetzner" situation.
Although since they were running a LEMP server stack manually and did their migration by copying all files in /var/www/html via rsync and ad-hoc python scripts, even a DO droplet doesn't have the best guarantee. Their lowest-hanging fruit is probably switching to infrastructure as code, and dividing their stack across multiple cheaper servers instead of having a central point of failure for 34 applications.
One of the new risks is if anything critical happens with the hardware, network, switch etc. then everything is down, until someone at Hetzner go fixes it.
With a virtual server it’ll just get started on a different server straight away. Usually hypervisors also has 2 or more network connections etc.
And hopefully they also got some backup setup.
It’s still a huge amount of of savings and I’d probably do the same of I were in their shoes, but there is tradeoffs when going from virtual- to dedicated hardware.
As the other person already said here, this blog post comparison is skewed.
BUT
EU cloud providers are much better value for money than the US providers.
The US providers will happily sit there nickle and diming you, often with deliberately obscure price sheets (hello AWS ;).
EU cloud provider pricing is much clearer and generally you get a lot more bang for your buck than you would with a US provider. Often EU providers will give you stuff for free that US providers would charge you for (e.g. various S3 API calls).
Therefore even if this blog post is skewed and incorrect, the overall argument still stands that you should be seriously looking at Hetzner or Upcloud or Exoscale or Scaleway or any of the other EU providers.
In addition there is the major benefit of not being subject to the US CLOUD and PATRIOT acts. Which despite what the sales-droids will tell you, still applies to the fake-EU provided by the US providers.