If you can, please provide few 1080p+ lossless images from the game, and I'll gladly prove you wrong.
Maybe it's a joke and I don't get it because of my poor English. I'm not an expert in image processing, but I am a mathematician with enough background in the field of data compression. Take an 1080p and a 720p versions of the same image in the same lossless format, and apply the same lossy compression on both of them, it's certain that the 1080p image file size will be larger than the 720p image file size. Maybe I wasn't correctly understood, so let me rephraze it in more detail. Take a scene, render it in 720p and apply a lossy compression on it. Render the same scene in 1080p. If you want the 1080p lossy file to match the size of the 720p lossy file, then you would have to use a much more aggressive compression.
Probably true, if you're playing on a sub 100$ 3,5" smartphone.
That's quite a demagogue statement, as I was referring a heavy lossy compression. Now I encourage you to try and find the difference between a downscaled and lossy compressed 720p and 1080p (you can use the original 4k image rendered by L&P) with the same file size on your 1000$ 6.5" smartphone from a regular viewing distance. While you may find some differences in a thorough examination, it won't be of any real significance.
L&P said himself, it's not an issue on his hardware
That's not true. He said that rendering wasn't an issue with in the context of rendering in 720p. As I said before, 1080p rendering time will be 2.25 times longer than 720p rendering time. And that may be an issue...
It's irrelevant what I think. It's L&P's promise, but yeah, I think 720p in 2020 is laughable.
I bet if L&P rendered everything in 720p and then upscaled his images to 1080p nobody would have known and nobody would have cared in the first place. Deep inside you know it, but hey, he promised...
And you know what, you're right about his promises. I also think it's absurd, and if he realized he's not going to render in 1080p then that promise should be removed from his last goal.