It's a hassle, as they're old machines and out of support contract (so we can't upgrade the firmware), and so far as I can tell there's no way to turn off public access to ntpd over the admin interfaces. We're stuck with having to go to the hosting company and change the cabling to route them through the firewall.
Just because you didn't set up ntpd doesn't mean you don't have it running (somewhere).
I would like to see servers demystified in general, and that's why I applaud articles such as this one that make the necessary counter-measures/workarounds plain and clear for those like myself.
I assume you mean that you interpret what I've said as implying anyone who does not know about NTP amplification attacks is an amateur server administrator. I do not mean to imply that. I simply mean that for people like myself, who are in fact amateur server administrators, this sort of down-to-earth style of article (here is what the problem is; here is how to deal with it) is very welcome.
Although it's only academic at this point, I am curious why you think I used the word "amateur" pejoratively and what category you believe I am describing in error. I ask simply because I'd like to avoid making similar errors in the future.
As far as I am aware, I am not responsible for any Internet-facing NTP servers (I certainly never set one up willingly), but it's good to have this in the back of my mind now in the off-chance that I ever do set one up.
I did have one of my Windows machines used for DNS amplification. I wrote about the incident [1] at my blog because I had been a bit surprised that it was not sufficient to simply disable recursion. That much had seemed like common sense, and I thought I had been so clever and thorough in turning it off. But later I found attackers were leveraging my server's willingness to provide a list of root DNS servers in response, even with recursion disabled. I ended up deleting the list of root servers and the problem went away. (Though, to be clear, I never ran the incident by any DNS experts, so I may have misdiagnosed the whole thing.)
I don't know what else I don't know about amplification attacks, so reports such as yours are helpful for people like myself who find it fun to run our own servers, but don't consider it an area of expertise.
[1] http://tiamat.tsotech.com/dns-amplification