The closed question is too broad because it is insufficiently precise to be answered within the guidelines in the help center. It is asking nine (count 'em, nine) separate questions. The excessive broadness is also nicely demonstrated by the fact that in the four or so years it was open, it gathered nothing that I would consider a complete answer to the question posed. It's also a very nice example of an X-Y question, which isn't enough by itself, but certainly doesn't help.
If you'd like, I'd be willing to switch it over to being closed as off-topic instead, as the question deals with the behaviour of user-level desktop software, which isn't generally considered on-topic.
It was locked because that way we get the nice little "historical significance" marker down the bottom. I'd take it off if I thought there was the slightest chance that the question might get the reopen votes required to override the close, but... yeah.
Jeff's question stays open because it is not too broad, it deals with a sufficiently well-defined problem, and it attracted an answer which addresses the question asked. I strongly disagree with the assertion that you need to know the full and complete behaviour of every browser when presented with multiple A records before you can show that it's a bad idea.