What's Secretly Destroying Your DnD Campaigns

What actually ruins your D&D campaigns? Hint: it might not be scheduling. Instead, let's talk SCOPE MANAGEMENT, which I think most people also have problems with.
Original West Marches Blog Post: arsludi.lamema...
Mike Shea's Poll: slyflourish.co...
r-meme-exe's original poll: / after_i_couldnt_post_i...