I think this is very common for tmux usage in general. I think the reason is that terminals seem to benefit the most from tiling WMs, as generally their own internal window management is quite lackluster and you usually want to open many terminals side by side. If you don't have the luxury of a tiling WM (or just want a simple-no-yak-shaving-required WM like Gnome), then tmux can be a real life saver.