i3 shows title bars (shrinking or expanding them) kind of like how tabs are displayed in a web browser. If you do nested layouts with i3, though, you wont be able to see all the title bars, but otherwise usually you can see all the title bars (though truncated to fit). That's a pretty common workflow, and it gives you "perfect vision" of all the windows in that workspace. Vs niri which by default scrolls the whole window (title bar included) off the screen, so you can't see all the windows in the workspace at a glance.