I might be wrong, but the people making the mistake aren't usually making it twice are they? I would assume that it's new people posting. And we know that like 25% of people read the rules. And half of them will remember them.
Anyways, if we demand a prefix, we're just going to tell them to use the prefix when they mess up, as opposed to asking them what version. Same number of posts, same problem, same message. One just has another rule. =/
If you're annoyed by asking for the version, prepared to be annoyed by telling them the rule every time.
Why not just put a reminder on the tech forum's create topic page? I've seen forums use this way before, and it works quite nice.
