This is now built into GNOME. You can set it under Displays
I'm happy just using KDE Plasma, XFCE and i3wm and not having to care about whatever Gnome is doing (except when changes to GTK affects the rest of the ecosystem, like their client side decorations which make Gnome apps look out of place).
Who said that? You can always decrease brightness on a Linux laptop since the first gnome, I myself have gnome3 installed on 2 laptops and the brightness buttons are working perfectly fine.
Redshift manages to decrease brightness even further.