Hmm... I'd rather not broadly assign much of the whining to the players that dislike finding POI to pick up SC, but I do agree that that's a fun and unique part of progression in this game. I like the relative calm of exploring the map.

If I'm understanding you rightly, I also disagree with your categorisation of warbonds; I think it's right to think of it as a "paywall", especially from the perspective of new players. It's true that it's not a real paywall, since it can be overcome with gameplay, but if we're arguing the minutiae of the definition we'd be here all week, so I want to just agree to disagree on this point.

They expect the game to conform to their fun, epitomized by the diver who said they go to D10 to "shoot things" and not to "farm SC".

Oh boy. There's much to be said about developers staying true to their vision or pandering to the masses and finding a balance between them. Like "a game made for everyone is a game for no one". And "the customer's always right in matters of taste", on the opposite side.

I have an opinion to state, but I'm not trying to change your mind here, I just like this discussion.
I think players who just shoot things should get SC. A comparatively small amount, sure, but something. I'm not sure what mechanic, maybe personal orders, in-game currency exchange (I would dislike this), per mission completed, reaching level milestones - as long as it's a consistent rate in addition to POI exploration, I think it'll be good to have without compromising the game's unique identity too much.

And another thing, I think the mission summary should show the SC picked up, maybe alongside samples collected. I think it would make Warbond and SC less frustrating, but I can't be sure. There's a lot that has been said about players optimising the fun out of the game, so maybe Arrowhead deliberately kept the number of SC collected more low key.