Why nodejs in frontity

So, I want to understand why we are using nodejs in frontitiy. ReactJS is perfectly capable of sending API calls and capturing the JSON data to render HTML.
So why is there a need to add a nodejs server in between ?

Guys, no answer. anyways, i got the answer, thank you.

I am interested in this aswell. What is the point of the frontity server? Can’t I just serve the static files via nginx or something else? Do I need the server? Unfortunately the documentation about this is extremely lacking.

I am currently evaluating a few different things for a new website and running an extra node server is not something I plan on doing.

PS: Unrelated to this, but when creating an account for the forum just now I had to completely change my pw generator settings because of useless pw requirements (apparently just having a 60 character password is not enough, it also has to contain numbers and weird capitalization)

The nodejs server is going to generate all the data in json files and store it in the server. So, when you publish a new blog on your WordPress site, frontity will tell the nodeJs server to generate the new JSON files (also called the Build step). And when any user opens your site, it is just going to send the already generated json data. So no database hits.
Since Frontity is already forsaken after Automattic took over the core team. You have WP GatsBy or Cloudflare pages to try out. I have move to Cloudflare pages for my headless project and it seems to be a great alternative.