Ah, but it is no longer a mathematical discussion, it is a software discussion. The generation of random numbers is a difficult business. If a particular piece of software or worse a random number generation function is compromised such that what it generates can be predicted, even within a range of possibilities, it fundamentally weakens the software.
I did kinda wonder if the breakthrough was to break an older form of encryption quickly so that they would be able to read oodles of stuff they had previously stored. Sure there’s time sensitive data, but a lot of it is not.