The problem is not really about if the images are lazy-loaded or not though, the author is using the wrong format for the images. There are just 16 images, but each one is over 10MB big because the author is using PNG for photographs, when they really should be using JPG instead.
There is literally no reasons to prefer PNG over JPG in this specific scenario.
I find it amusing that you (and others) presume why some did a thing. Their motivations.
If you want something stored for historical reasons, shared by media, news, archive.org, png presents unvarnished stuff.
5, 10 years from now, people will scratch their head, and wonder why people cared about such tiny filesizes.
FLAC used to be only for extremists too.
I downloaded the 1.png file and converted it to a JPG and also diffed the origianl PNG with the JPGs I generated (90% in quality and 80%).
- Original PNG: 51M
- 95% JPG: 13M
- 90% JPG: 9.4M
- 80% JPG + interlace + strip Plane: 4.7M
Comparing the new versions with the original via the PSNR metric (closer to 1 is better [more similar]):
- Original PNG vs Original PNG: 1 (obviously)
- Original PNG vs 95% JPG: 0.999465
- Original PNG vs 80% JPG: 0.998611
With other (shorter) words: There is no difference for the consumer (a website visitor) between the two, except one uses more resources (RAM + network) and takes longer to download and the other one doesn't.
For the archiver (which you seem to consider more than the website user) there is clearly a difference between lossless and lossy files. But those can be linked instead of rendered directly inline.
https://l3ouu4n9.github.io/2021/note/BHUSA/1.png - 37 megapixel - 50MB.
This image could have been scaled down from it's current dimensions of 9894x3786 down to say 1920x210, and it would still probably contain basically the same amount of information really.