I for once can’t stand the idea of having my editor run inside a browser…

Well, don't run it inside a browser then. There is no need to get agitated because of that option. But this is super useful for universities and other organizations that educate people. They can run these preconfigured IDEs for their students and execute the code on the same server, so that even if you have something like a Chromebook, you can participate in classes. This is what places like Harvard do, and this is how Microsoft introduces CS students to VSCode and other products.