Why would Srila Prabhupada neglect to mention something as important as this ritvik system in writing?
Why? Why? Why?
He did. The written instruction signed by him to be sent to all temple presidents was obfuscated, along with the numerous tapes of him discussing it with his disciples.
Ritvik system will disappear in future very soon. They are just group of devotees who are reluctant to accept teachings of Srila Prabhupada and our previous Acharya.
Like ISKCON is disappearing? Attrition rate of 99%...
With regard to the last point debated, the detractors are arguing the Śrīla Prabhupāda wrote it was custom 'not to initiate in the presence of the Spiritual Master', which is at best indirect evidence by the detractors of the ritvik posthumous system. It is by no means comparable in common law evidential 'weightiness', to a written document regarding future initiations signed by the Founder-Achārya of ISKCON (that was to be distributed to all contemporaneous temple presidents). Maharaj argues that obfuscated evidence (tapes presumably removed from the ministry and later destroyed) proves that Śrīla Prabhupāda did not expound on this ritvik system, which is highly-irrational and illogical at best. Other considerations such as providing motivation for premature removal of the Achārya by ambitious disciples (as occurred with HDG Śrīla Bhaktisiddhanta Maharaj) was not discussed. Very unconvincing and amateurish performance by the detractors. Jaya Śrīla Prabhupāda.
Why? Why? Why?