Looks just like VS Code and I think it’s still built on electron so take that as you will.
I feel like browser support is such a niche. I don’t understand why many IDEs dedicate so many resources to make it work on the browser. There are already many options to code on the web if you need it.
Pretty sure it’s to enable extensions written in JS. These apps build their success on a rich ecosystem of plugins. And, like it or not, JS plays a big part in that.