[WilliamEdward]

You've managed to say their analogy is bad in two paragraphs without even explaining why it's a bad analogy. You even admit you don't really understand what they were trying to say. Poor explanation, or poor understanding?

[ofibrvev]

If an analogy requires more explanation than the original concept what purpose does it serve?

I think in this case at best the analogy grossly oversimplifies the issue. If it really were just a “screwdrivers” problem as explained then the 2 to 3 migration would have been mostly trouble free and would have happened. Clearly it did not go that way so that analogy can not possibly be appropriate.