Agreed and I'd like to expand on the "test my custom" to "everything."
At work I run and admin web servers, mostly Apache. I choose Apache because I have the most experience with it and have developed a feeling for how much I can trust various configurations. I don't have that level of experience with Nginx. However, I like Nginx better and feel like it would be better suited to meeting our business needs. So I need to spend a couple years getting better aquainted with Nginx, what can go wrong, how they find and handle security issues, how quickly patches come out, how easy it is to handle stop-gap measures, etc.
I can only do that somewhat freely at work because there are different restrictions on what I can do with machines at work and what I'm willing to have fail at work. If I can run Nginx at home for a couple years, I don't have those restrictions. It's hardly reasonable to consider my hobby tinkering a business and unreasonable for me to have to upgrade to a business class service just to give me the ability to ensure I understand how to configure the hardware, software and services I am trying to learn.
I tried FreeBSD for a while at home. I absoutely love some aspects of it. After a couple years, I decided I didn't like the upgrade cycle, but I didn't learn that at work and shouldn't have to. I tried OpenBSD too and discovered some drivers didn't like some of the hardware I was using and that would have been a misuse of my time to discover at work since they don't pay me to play around learning new stuff. I'm a better admin professionally because of my hobby experience at home.
I too had to ask and answer "what is a server?" I have an old Cisco router a couple switches and a 1U server with no onboard hard disk. The Ciscos have built in telnet and web server interfaces. Even my wifi router has an onboard web server for configuation. Surely they wouldn't consider the Ciscos and wifi router servers? Of course not. The 1U dell needs a tftp server to function and can run various systems but none of them necessariy have to offer externally available software servers of any sort. That doesn't sound like a server to me either. In the end, I try to keep my homework limited to a couple things I'm tinkering with and not offer anything the general public might be interested in from my home connection and I believe I'm operating within the spirit of the rules. That doesn't stop me from wishing that the rules were actually more clearly established along reasonable lines. As an admin of a network myself, I believe that it is my job to ensure not only that we have clear rules about what is allowed and what isn't but also to ensure that dangerous or abusive use is curtailed by technology, not a "you find out that you broke the rules only after you've gone far enough to be punished" approach.