Google Docs was built for documents: letters, reports, shared notes. A novel is a document too, technically, but it's also a hundred thousand words of interconnected structure, characters, and world detail that needs to stay consistent from page one to the end. Docs doesn't know the difference. Here's exactly where that shows up.
No real chapter or scene structure
In Docs, a "chapter" is a heading you typed and a "scene break" is a line of asterisks you remembered to center. Nothing about the software understands either as a distinct unit. You can't drag a scene from chapter six into chapter four. You can't collapse a chapter to see just its scenes. The document outline panel gives you a clickable list built from your headings, which helps navigation, but it's a read of your formatting, not an actual model of your book's structure.
No manuscript formatting built in
Industry-standard manuscript format (Times New Roman or Courier, 12pt, double-spaced, half-inch first-line indents, centered chapter headings) exists because agents and editors read hundreds of submissions and need a consistent, easy-to-read baseline. Docs can be formatted this way, but nothing in the software enforces it or checks it. Every deviation, a stray font size, an inconsistent indent, is something you have to catch yourself, usually by scrolling through the whole manuscript looking for what's wrong.
No outlining tools
Planning a novel's structure, whether that's a three-act shape, the Save the Cat beat sheet, or something you invent yourself, happens outside Docs entirely. Most writers end up with a second document, a spreadsheet, or a separate app just for outlining, then have to keep that plan and the actual manuscript in sync by hand as the story changes during drafting.

No character or world-building tools
A novel with more than a couple of characters needs somewhere to track eye color, backstory, relationships, and arcs, consistently, across however many months it takes to finish a draft. Docs has no character template, no gallery, no structured way to hold any of this. Writers improvise with a second document per character, a spreadsheet, or sticky notes, and the details drift out of sync with the manuscript the same way an outline does.
World-building has the same problem, multiplied. Maps, timelines, invented economies, and history exist, if they exist at all, scattered across whatever tool each writer happened to reach for.
No clean export for submission or publishing
Exporting from Docs to .docx or PDF carries across whatever formatting is actually in the document, inconsistencies included. There's no formatting pass, no check for manuscript-standard compliance, no single "export correctly" button. Getting a submission-ready or upload-ready file out of Docs means fixing formatting by hand right before you need it, which is exactly the wrong time to be doing that kind of work.
What this actually costs you
None of these gaps make Docs unusable. They make it a tool you have to build a system around, usually by adding two or three other apps and keeping everything manually in sync. A dedicated novel-writing app closes these gaps by design. Quillen, for example, formats to industry standard automatically, gives chapters and scenes real structure in a sidebar tree, and includes outlining, character profiles, and world-building in the same app as the manuscript, so there's no second tool to keep synchronized.

Common questions
Is Google Docs bad for writing a novel?
No, it's a reasonable place to start. It's free and familiar, and drafting works fine. What it lacks is anything built specifically for a novel: chapter and scene structure, manuscript formatting, outlining, and character or world tools. Those gaps matter more the longer the manuscript gets.
What do novelists use instead of Google Docs?
Options range from general tools like Scrivener to fiction-specific apps like Quillen, which builds manuscript formatting, outlining, character profiles, and world-building into one app rather than requiring Docs plus a stack of separate tools.