Does Sikhism exist universally? If that is the case, why has it not yet been accepted?

Respected Chinu Ji;

Thank you for asking. Your question is in two parts and I will try to address it one part at a time.

The answer to first part of your question is resounding yes. Sikhi exists universally.
The SIkhi is about understanding of the Creator and the Creation, the universe. And understanding one’s place in this well inter-connected Universe. Please allow me to refer a verse from Sri Guru Granth Sahib.
ਸਭੁ ਗੋਬਿੰਦੁ ਹੈ ਸਭੁ ਗੋਬਿੰਦੁ ਹੈ ਗੋਬਿੰਦ ਬਿਨੁ ਨਹੀ ਕੋਈ ॥
sabh gōbind hai sabh gōbind hai gōbind bin nahī kōī .
Creator is everywhere, there is nothing / nowhere without the Creator.
That is the Sikhi Philosophy.
In SIkhi Creator is not confined to the Mandirs, Masjids, idols, or in certain Devta, or Prophet forms. So Sikhi is Universal.

Second part of your question is relatively simple. Before Sikhi appeared on the stage, there were many a faiths in the world and most of them for the benefit of the clergy. The clergy has taught the common man plenty of rituals and concocted stories about after life and sorts of superstitions. It is very difficult for the common man to unlearn what they and their fore fathers have practiced for hundreds of years. Only a few could understand and accept the truth of the universal laws, Sikhi, taught by Guru Nanak. Those who could, accepted Sikhi. Rest of the world is slowly beginning to understand the falseness in manmade stories and rituals and slowly getting away from the formalized religions. Even though unknowingly step at a time they are adopting Sikhi way of life. They call it Humanism.