So - to me, for how I DM. The Warlock's pact is a story-driven difference between it and other arcane classes. Other, externally driven classes (cleric), indeed do require external inputs.. however, running off established theological principles and gods (which aren't expected to form a personalized pact or speak directly to the PC) just play out much easier or more naturally from the DM side of things. As for how I DM these by-case Warlock characters.. if the player wants to explore their patron, and gets a high level feature to do it, I'm not going to say "jokes on you, the patron says nothing"... it may be funny but it also seems lazy.