I'm honestly just really annoyed about this "society and environment"-spin on advise that would have an otherwise niche, but perfectly valid reason behind it (TFA: slow satellite network on the high seas).
This might sound harsh and I don't mean it personally, but making your website smaller and "being vocal about it" (whatever you mean by that) doesn't make an iota of difference. It also only works if your site is basically just text. If your website uses other resources (images, videos, 3D models, audio, etc.), the impact of first load is just noise anyway.
You can have a bigger impact by telling 100,000 people to drive an hour less each month and if just 1% of your hypothetical audience actually does that, you'd achieve orders of magnitude more in terms of environmental and societal impact.
Now, it is true that it didn't save much because probably many people were uploaded 8K videos at the time, so drop in the bucket. But personally, I found it quite inspiring and his decision was instrumental in my deciding to never upload 4K. And in general, I will say that people like that do inspire me and keep me going to be as minimal as possible when I use energy in all domains.
For me at least, trying to optimize for using as little energy as possible isn't an engineering problem. It's a challenge to do it uniformly as much as possible, so it can't be subdivided. And I do think every little bit counts, and if I can spend time making my website smaller, I'll do that in case one person gets inspired by that. It's not like I'm a machine and my only goal is time efficiency....
Depending on the type of video this may not matter, but it often does. For example, my FPS gaming and dashcam footage gets utterly destroyed if uploaded to youtube at 1080p. Youtube's 4K seems roughly equivalent to my high bitrate 1080p recordings.
Plus, trying to signal your way to societal change can have unintended downsides. It makes you feel you are doing something when you are actually not making any real impact. It attracts the kind of people who care more about signaling the right signals than doing the right thing into your camp.
And no, a million small sites won't "become a trend in society".
