That was an inadvertent insinuation on my part, I apologize for not being more clear about it. A formal commitment between guru and śiṣya is one of the key functions of the dīkṣā ceremony itself and it quite important.
It is similar to the importance of a marriage ceremony for a husband and wife. In the bottom line the ceremony is not always essential and certainly doesn’t need to be elaborate – it is the actual love between the couple which forms and sustains a marriage bond – but the impression (saṁskāra) made by a marriage ceremony and the marriage vows is very, very often a very big help in keeping the couple committed to one another through difficult times.
In my articles about the guru-śiṣya dynamic, my intention was not to denigrate the importance of dīkṣā but to emphasize the importance of śikṣā which, I believe, is currently very under-emphasized.