I never noticed it before, but it seems to me that Moroni is expressly channeling Alma’s famous sermon to the people of Zarahemla in his letter to Pahoron. It seems impossible to read this verse and not be reminded of Alma’s penetrating questions:
“20 Have ye forgotten the commandments of the Lord your God? Yea, have ye forgotten the captivity of our fathers? Have ye forgotten the many times we have been delivered out of the hands of our enemies?”
These are the exact questions that Alma begins his sermon with when he asks whether they still remember the captivity and deliverance of their fathers.
So what was Moroni accomplishing through the repetition of these questions? It seems to me that he hoped to do a couple of things: 1) link himself rhetorically to the great Alma; 2) hope to inspire Pahoron to remember Alma’s stirring words and to be called to repentance; 3) give his planned insurrection legitimacy by linking it to Alma’s call to repentance.
It seems to me that Moroni is doing something similar to what modern politicians do when they invoke Ronald Regan or Martin Luther King Jr. He is linking himself to the legacy of those that are seen as great.
It is also possible or even likely that Pahoron and perhaps Moroni himself may have been there to witness Alm’s sermon which was only delivered about 20 years prior. And there were many living contemporaries who had been there. So this allusion was likely purposeful and had special resonance.