Its not the dominant Vedanta doctrine. Only a small percentage of Hindus believe in Advaita. Isn't like 60% of Hindus Vaishnava? Im really asking to, not trying to be smart. I heard that about 10% of Hindus are Advaita Vedantist, please tell me if I am misinformed.
I don't think anybody can tell you exactly what percentage of hindus believe when it comes to this subject.
I have heard many Vaishnava claim that 75% of all Hindu's worship Vishnu. How can they know. Just look at all the villages in India and Nepal are you telling me that people walked from town to town taking polls.
I went to a Vishnu temple in Orissa when I asked them who do they follow Chaintia or Madhava they were insulted and said no Sankara. Also the Vaishnava Pusti Marg sect seems closer to Advaita in many ways they look down on the followers of Chaitanya and won't eat the Prasad from them.
I know a South Indian Family who say they are Vaishnava. Yet when asked in detail about it they say they are Smarta. They call themselves Vaishnava because they worship Vishnu in the Smarta Tradition.
In the Punjab a majority of Hindu's seem to be very influenced by the Sikhs and Arya Samaj. In Bengal Mother worship is very popular, Ramprasad is as well known as the Lord Chaitanya.
I have been to villages that I can't even tell what sect they are. They worship snakes and Trees. One main God in one village is 1/2 Dharma and on the back side of the Image is Yama. How do you define this sect?
An all India poll was taken (apparently only among the middle class and rich who have phones) Asking who was the most Important Hindu religious teacher in modern times. It was Swami Vivekananda that came up on top not a Vaishnava.
I believe that it is impossible to know exactly what the common Hindu believes. Such a study has never been undertaken as far as I know. It is also true that the difference between most sects that worship Mother and Shiva differ very little from Adviata's Monism.
I am willing to say that Vaishnava sects are the most popular in India. It is just that I am not even sure that most Hindu's are even a member of any sect.