Not necessarily. When I worked at Yahoo, in Australia (what a glorious time that was) 25 years ago, I built servers in the datacenter using PXE. It was anything but slow.
Unbox a server, plug it into the PXE network, boot it. It boots to a miniscule FreeBSD distribution and you use a common user/pass to log in. Then, you type clone -h <fqdn> and it mounted an NFS share and installed packages and config files for that hostname. In three minutes or so your server shut down and you racked it up, plugged it into the production network and it started accepting work, or it notified the engineers in the US that it was ready for use and they’d add it to a pool, then it would start handling work.
It was extremely slick.
The build network was secure because you could only access it in secure areas which had the build network and a build server deployed to it. So security was not a problem.
Why can’t I set up Windows or MacOS like that? I know the answer I just find the answer annoying.