It’s not about looks, it’s about functionality. I could add a hundred lines of CSS to make it sparkle without touching Javascript. I could think of a dozen convenience features that would require Javascript, but none that, if disabled, would prevent the search bar from functioning as a search bar.
When I was on Hyprland, I had to start Firefox with
XDG_CURRENT_DESKTOP=kde
while having both the KDE and GTK implementations of XDP.