Seriously, if all the web looked like this it would be more complicated to use for 99.9% of the world, so it would have remained a niche, so its overall usefulness would have remained limited.
Instead, talented hard-working people put lots of effort into making the web look a much more friendly place. This has made the web a much more inclusive place, and thus, much more of the world has started to use it.
RMS is a brand, and this 'zero design' is part of his brand. You already know who RMS is before you visit his site, and if you don't, you probably aren't part of his 'target market'. The jarring "Oh the CSS hasn't loaded" moment is precisely what he wants you to experience. The kind of people who visit his site know how to use reading mode on their browser, are comfortable adjusting the line width in whatever client they are using, so it doesn't matter.
It doesn't mean that the rest of the web would be a in a better place if it had remained looking like this. It would have remained an obscure corner of the world where a group of geeks met, and so many of the benefits of the internet would never have transpired.