That is the only explanation I have for why one writer is slain by the antagonists that pop up in the middle of her writing journey. While, another writer faced with the exact same problems is able to effortlessly make her way forward.
Or, perhaps, the answer lies in the understanding one has of the task itself.
The writer who is slain may have heard rumors about the meddlesome, messy, sagging middle but when confronted with the reality of writing her way through the middle, takes the challenge personally, surrenders all her power and gives up (either for the day or for months or even years).
Another writer has researched not only the setting and authentic details needed for her story but also the craft of writing itself enough to understand that the antagonists that arise in the middle are not to be feared or felled by or taken personally but part of the process itself.
I'm not explaining myself well here and the reason could be because this more informed writer is an anomaly to me. She has only been writing for two years and is well beyond the halfway point to creating a compelling novel. Though slowed down by the antagonists in the middle, rather than create resistance by judging herself as the problem and throwing herself against the wall or curling up in a ball for years before seeking help, she reaches out almost immediately and is now off and flying again.
Replace the story you tell yourself about writing the middle of your novel, memoir, screenplay from one of threat and opposition to a story of strength and determination. Antagonists are self-created and have power over you only so long as you give away your own personal power first.