Bare metal makes such a big difference for test and CI scenarios. It even has an integrated a GPU to speed up webdev tests. Good luck finding an affordable machine in the cloud that has a proper GPU for this kind of a use-case
Running on managed bare metal servers is theoretically the same as running any other infra provider except you are on the hook for a bit more maintenance, you scale to 20 people you just rent a few more machines. I really do not see many downsides for the build server/test runner scenario.
Consider that even VC-backed Google started out with lots of cost saving measures in place. Once they brought their second datacenter online, the way they uploaded the index to it was Lucas putting a big stack of hard drives in the boot of his car and driving across the USA to plug them in. This continued for a while until they were able to strike a special deal on bandwidth.
That was just one of the unconventional things they did to save money. Using Linux was another. Although we now think of what Google did as obvious, at the time it was considered bizarre and radical that a search engine company - a software company - would rack bare motherboards onto corkboard bases, just to save money. All their competitors were running on commercial UNIX big iron.
https://www.datacenterknowledge.com/hyperscalers/looking-bac...