I think the main point is that readers rarely experience the I've-got-to-turn-the-page tension without tension of some sort. A good read is one where I know the couple is going to be tested before they get to their HEA. That kernel of doubt is what keeps me reading after midnight. How the author accomplishes that is another story.
I think it's about balance and believability along with reader preferences. Some readers want to see the h/h take on the world, some want to get lost in another person's inner world and don't want to read about the villain's evil plot.
External conflict can create internal ones so that the separation isn't always so distinct, imo. A deep inner conflict really draws me in. I become more invested in wanting a happy outcome for a character who's struggle with their inner demons.
Sometimes though, too much inner conflict can wear me down, especially if it seems like the character is so wrapped up in what's going on inside them that they come off weak, needing another to "fix" for them, and self-absorbed. After a while, I just want to shout enough already!
To me the black moment doesn't have to be a catastrophic event, it just has to bring the obstacles to a head so there's some new understanding gained that will build a foundation for the HEA. It could be something totally innocuous that sparks a tumbling out of unresolved issues.
Cathy C, tell us more why you think a "black moment" should be and how yours differ in such a way that you don't consider them to be, well, "black moments".
Thanks for posting the link. It touched on some issues I sensed my first story missed ( like the ticking clock).