On the subject, the whole concept reminds me of House of Leaves, only the later is definitely more weird
But in this case, this is just a hipster website. The slow loading time is purely coming from the content. When NYT first did "Snowfall", people were trying to grasp onto anything that "might be the future of journalism", so that "rich format" took off for a while, but now people know better, these rich format articles have terrible ROI because creating them is really hard and not scalable, and in many cases it wastes a lot of traffic, and last and most importantly, readers couldn't care less about this "rich format" journalism. It's just the journalism people circle jerking about how "beautiful" it is.
Which is why this format mostly disappeared. That said, I have never seen anything THIS bad. I am leaving all these comments here because I am genuinely annoyed that they messed up the reading experience on a topic I was actually interested in reading, so bad that I decided not to read it.
I suspect the main reason people do it is because progressive loading has the potential to leave your page half-rendered, which looks bad. So you block the whole thing until you can present it in its entirety.
But it's the web. We're used to pages half-loading, and we're used to starting to read text before everything has been loaded. The right way to fix that problem is to make your design more lean, not to stick everything behind a 15-30s loading spinner.
So if you are still interested in the content, you should try opening the page again. It may work.