If this was the case then the Khanda De Pahul ceremony and the recital of Nitnem Banees would take place with only two Banees (Japji Sahib and Anand Sahib). This would also mean that there would be no Ardas (as the opening sections are from Chandi Di Var). Hence Sri Dasam Granth plays an important part in the three important aspects of a Sikh religion, namely Amrit, Ardas and Nitnem.
Hence Sri Dasam Granth is an important Sikh canon second only to Sri Guru Granth Sahib.
Interestingly this idea of a mutilating and destroying the Sikh scriptures was advocated by Teja Singh Bhasaur in the early 1920’s. He was excommunicated from the Sikh fold for not understanding the role that both Sri Guru Granth Sahib and the Sri Dasam Granth played in the Sikh psyche. Similarly the Akal Takht has ruled against those who have failed to grasp the idea of Miri-Piri and Sant-Sipahi including modern day atheists and communists in the garb of Sikhi. Most recently even an ex-Jathedar of the Akal Takht was found to be ignorant of the basic concepts of the Khalsa panth.