I actually found it to be not that terrible in comparison to some other sites that are out there today. Medium loads 17 scripts totalling about 2.4MB of js. For comparison, reddit loads 78 scripts totalling 7.5 MB.
Is it heavy for such a simple blog? Yes absolutely. Is it heavy for a modern React app? Not really. I think the crux of it is that we often rely too much on heavy frameworks for React even for simple things. It's definitely an antipattern in development today.
For an app like medium, client side react with that many dependencies is perhaps not the right approach in the first place?
Server Side Rendering(react or w/o react) would be a better way to do serve their content and have the added benefit support users who have no js support (noScript , terminal based browsers, screen readers? etc)
I just checked one of my longer articles and my website loads 11678 bytes including the article and 23.39kb, including CSS, custom fonts and and images.
I would think that 0.5mb should be more than enough.
Is it heavy for such a simple blog? Yes absolutely. Is it heavy for a modern React app? Not really. I think the crux of it is that we often rely too much on heavy frameworks for React even for simple things. It's definitely an antipattern in development today.