The rule does not stand.
You said that "You can't develop timing without a metronome." Which is simply not true.

You should have said "Most people cannot develop timing without a metronome". What you said essentially is, it's impossible for someone to have timing without using a metronome.

Yes I did say that, I do not believe it is actually impossible.

But if someone asks how to improve technique, always tell them to use a metronome. If they were good without it, they wouldn't ask for tips. That's pretty much what I meant.

well I can agree with that =)

Yay. Now let's go eat a sundae together.

you could always check up some exercises from Alexi Laiho, those really helped me back then lol.