That is an essential point.
It also happened in Australia and New Zealand.
The signficance is that the the gun confiscation laws were extreme and precipitous (they did not evolve, they happened all at once). The effect was that violent crime went up immediately and a lot.
The reason that this is so essential is that the gun control debate has never had such a clear, controlled experiment about the effects of gun control. The gun grabbers can argue all the theory they want, but there are now clear data about the real effects.
Stalin once said "I won't let the people have the vote. Why would I let them have guns?"