I don't think of the things you listed as "topics". Browser, code, slack, etc.. seem more like tasks or activities to me.

I used to use i3 on a 49" super ultrawide monitor (32:9) and when I did each desktop was truly a topic, with a deep arrangement of windows on it and tabs to switch different areas over to different tasks.

My primary interest in tiling window management is being able to see all of the things that I need to see at once, at once. For me, it's all about context-- placing related windows next to one another. It seems like for others it's about being able to switch between a limited set of fullscreen windows quickly.

I like that Niri gives me a flexible way to divide my workspaces by topic without the windows stealing screen-space from each other. It doesn't feel much like hunting for windows, it feels like... a materialized view of alt+tab. Maybe I have a browser to the right of my editor and a terminal to the left. I can quickly shuffle back and forth between being able to edit while also seeing one or the other.

I even have this binding to cycle the columns to the right of the active window:

    Mod+Tab hotkey-overlay-title="Cycle windows to the right" { 
      spawn "fish" "-c" "niri msg action focus-column-right; niri msg action move-column-to-last; niri msg action focus-window-previous"; 
    }