@red61544Addressing the question from a slightly different perspective (i.e. not delving into exact word counts), editors typically don't dictate the story. Publishers do, and nowadays, publishers require submissions to be fully professionally edited, and will then reject any they find typos in. Luckily, publishers are not better at locating obscure typos than authors or editors, so most slip by completely united.
The key, is that the extra 50,000 words don't stand along by theirselves, instead they're part of the story. Mainstream authors have set word count limits, so authors know their limitations, so even when they do go over their limits, the story is solid enough it won't be very far off and the quality of writing will warrant the extra size. Those conditions do NOT apply to SOL!
Aside from extraneous subplots and unnecessary filler words, it's hard to cut a chapter without crippling an existing story, and every time an author rewrites a story (typically long after they complete it), the rougher and less wonderfully worded it'll be. Prose is typically not something you can force on someone, it flows from a love of the language, not from an editors demands, so the changes will stand out in stark contrast to the rest of the story.
But that's not what the rest of the thread is focusing on. The typical 100+ chapter SOL story is clearly on its own course, completely independent of the author original plot. Again, when you focus on the day-to-day life of a character, you can go on forever, and the 100th chapters will have little in common with the first twenty.
However, a editor will highlight when the story is going astray, and a Content Editor will pick that up immediately! Proofers however, are solely focused on typos, often ignoring the direction of the story. The other editors are generally in sufficient demand, they won't stick around for a 100+ chapter story, as they have much better uses for their time.
Also, it's difficult to criticize bloat in a jerk-off story, where the whole issue seems to be continually adding additional characters just to prolong the story, often with little obvious plot elements.
Generally, editors recognize when a story has little focus, and they'll abandon ship early, rather than getting trapped in something that's slowly spiraling out of control, ratings be damned. Instead, authors stick with whoever signed up, and if they don't hear those competing voices, they never know when their story has lost focus.