What's to stop me from repurposing my miners to continuously generate new addresses? It doesn't seem like it would take long to generate a significant chunk of the key space.
There's no chance that this will ever be profitable.
I'm just playing devils advocate... I'm not worried about it one bit. However, as NicholasBell worked out, there is a chance. It's just tiny. I think people just want it acknowledged that it is possible, but very unlikely. You can't get to 0 with a constant, nonzero number. You can only get there if it works for every progressively smaller epsilon. However, expressing exactly how tiny the risk is will help people understand what steps (if any) should be taken to mitigate it. As I said, I don't think it's big enough to justify any mitigation.