I retract my claims. You're right. Thanks for calling me out.
I will say that it's... a gargantuan effort to do the things that you're proposing. But as someone who did them you're right, you can. (BigGAN-Deep took a year to track down the bug https://github.com/google/compare_gan/issues/54)
BigGAN-Deep is a decent example of the thing I was really worried about: replication. I thought it'd be really easy to "just implement the paper." But no one had. Mooch did, but not at the same scale as the DeepMind release.
Maybe you're right about me, too. You're convincing me that I'm not a very good ML programmer. It's probably best to bow out on whatever high notes I've achieved.
Karras' work is fantastic. I don't know why this preview of things to come was where I chose to do this. Thank you, nVidia group, for working so hard.