I don’t know how goths organized to the point where this was declared a day of unity. Goths are a lot like cats that way.
They argue amongst themselves most of the time.
They range from all black everything to pastel-clad lolitas with parasols.
There are pagan goths, atheist goths and Christian goths. There are Islamic goths.
Anarchists, socialists, communists and monarchists.
The unity is in living a subculture that is also counter-culture, in being visibly different.