Why does Krishna reject spritual practices and methods? || Acharya Prashant, on Bhagavad Gita (2020)

Questioner (Q): Does the realization of Truth happen only by Grace, and is it not in the sadhaka’s control irrespective of the sadhaka’s efforts?

Also, why has Sri Krishna categorically made a distinction between single-pointed devotion to Him, and Vedas, austerity, gifts, sacrifices? Because to me, devotion to Krishna meant the latter only.

Acharya Prashant (AP): Where is it written that the work put in by the sadhaka or the seeker (the practitioner) does not matter? The verse very clearly says, “But by single minded devotion, I may be in this form, be known, O’ Arjuna, and seen in reality, and also entered into, O’ scorcher of foes.” Nowhere has it been said that realization of the Truth happens only by Grace. What basis do we have to speculate, or imagine, or raise this kind of a concept?