> I had never heard of the ordering of the DNS servers being meaningful

Well, congratulations, there is a first time to have heard everything.

Ordering of DNS servers matters. For instance, you might have a fast one near-by (perhaps on the same machine or LAN segment); and a fallback one that is more costly to use (few hops of latency, more network resources).

> DNS is supposed to be reliable.

In that case, what you should never have heard of is people pointing to more than one DNS server simultaneously. They should have the one and only one which is reliable and that's it. (In fact, that is not an uncommon scenario; that DNS server does the recursion to others if it doesn't have the info.)