When the Gigafactory was first announced, it was shared that it would be able to produce more batteries than the rest of the world could build at the time combined. To have that same news be true 4 years later would be impressive, as the rest of the world has continued to ramp up its battery production capacity. That would be a notable feat in and of itself, but to stay on pace with that and then blow the lid off by a factor of two takes it to a whole new level.
Beyond just being an amazing feat and a great use of capital, the news speaks to just how far ahead Tesla is compared to the rest of the automotive companies in the world (combined). If a massive company like Toyota wanted to produce as many electric vehicles as Tesla, it would first need to source batteries. It could go to every other battery company in the world and start building its own factories but it would still be years behind Tesla … assuming the rest of the battery capacity in the world were even for sale.