Why lingayats are not Hindus? 

After Karnataka government agreed that Lingayats as separate religion and sent recommendation to the Central government to accept its plea, Lingayat religion, became a talking point in the social media and in the real world.  

I spoke to two professors who had deeply researched in religion and culture. Prof M N Mahadevappa  has sent me many notes and spoke to me in detail on rituals of Lingayats.
Prof Sarvanan who heads the Saiva Siddhantha department in the Madras University busted many myths.

Essence of what both of them said:
1)There is no separate religion called Hindu.
2)Saivism, Vaishavism, Gowmaram, Saktham, Ganapathiyam, Sowravam are six different religions which were later clubbed together as hinduism for political reasons and administration. 
2)Lingayats wear lingam in their chains but the linga that is seen in Saiva temple is different one. People often mix this fact
3)Lingayats are represented as sub caste in hinduism now whereas Basavanna who introduced this religion was very much against the caste system and varnasirma dharma.

Story link:
http://www.bbc.com/tamil/india-43489113