You did not answer the question. Reaching 0.7 exaflops also requires those logistics and ecosystem. You didn't say what changes when you reach 1.0 (because it's nothing).
It's an easy to understand mark on a very smooth difficulty curve. Not a barrier.
He asked what is significant about 1 exascale that it's a "barrier".
Now granted, the original rendition of this saying ("Breaking the sound barrier.") is also arbitrary because mach 1 is the speed of sound travelling through air on planet Earth, it's still a valid question that you did not answer.
Breaking the sound barrier isn't arbitrary. Indeed even measuring it using the Mach number shows that. Mach 1 isn't fixed, it is variable based on a number of attributes.
At Mach numbers above 1 the compressibility of the air is entirely different. The medium in which the airplane operates behaves differently, in other words. The sound barrier was a barrier because the planes they were using stopped behaving predictably at Mach > 1. They had to learn to design planes differently if they wanted to fly at those speeds.
Mach 1 is an external constraint mandated by the laws of physics. There is a good reason that sound can't travel faster.
That is why it is a barrier to be broken. It is a paradigm shift imposed entirely by the properties of our physical world.
