Editing is one of the most important disciplines in modern filmmaking. That's not to say that editing hasn't always been important in movies, but with the advent of nonlinear editing, the discipline has become more accessible than ever. As a result of enhanced accessibility, editing has become a ubiquitous skill for most people. Even people that don't possess a lick of film school knowledge can stitch together a decent Tik Tok transition video.
The dark side of editing becoming so commonplace is how frequently directors outsource an editor in favor of blocking a scene. Instead of structuring scenes where the cinematographer and actors know where to stand and when most directors shoot for "coverage." For those unfamiliar with the term, coverage is where a director demands several versions of the same scene to be stitched together in post-production. And while scenes shot for coverage are efficient, it causes movies to feel generic. However, there are other ways that editing can botch a film.
In the video linked above, the YouTube channel This Guy Edits explains how editing might have led to the commercial failure of the film Margaret.