Is it allowed to share original sites link without refferel links?
Absolutely Yes.
PS: May be not some shady website and stuffs but as long as it's a clean looking website and offering clean stuffs then I do not see any problem.
I want to clarify if someone shares refferel link with original site link, how can we spot that members intention actually helps the forum members or not?
By any means, referral links are not allowed with the original link or without the original link. (I guess in my very early stage I had one post with the original and referral link. I remember I removed it later)