Discourse is just as bad. A forum should not require the use of javascript. A forum shouldn't silently remove parts of the DOM that are off screen. A forum should allow me to load an entire thread (or however many posts it decides a page is) in my browser, and use the native browser search function to find things.
Discourse is what people want as a modern forum.
Two good examples are https://discourse.nixos.org/ and https://forum.level1techs.com/