I realize I expanded the scope by bringing Engels' "On Authority" into the conversation. I want to remain focused on Lenin's vanguard party as an implementation of the "dictatorship of the prolitariat". I agree that Lenin's ideas were informed by the writings of Marx.
Marx's "dictatorship of the prolitariat" could be implemented as a vanguard party as per Lenin. Lenin's iteration could be construed as accurate to Marx's definition.
However, Marx also referred to the Paris Commune as a "dictatorship of the prolitariat" even without a vanguard party. Therefore my qualm, similar to the original comment, is that Lenin's vanguard party is a method to extract rents from the prolitariat.
I haven't read much Trotsky. Thank you for the recommendation. I will give it a read. My fault with Lenin has been the mechanism by which the vanguard party relinquishes power to the prolitariat.