Over the past few years, I’ve encountered countless startups that claim they are going to disrupt or revolutionize book publishing.

I once thought we might see one of those take off. Today, I’m not so sure. Book-related startups face a particularly tough path forward. Here are a few reasons why.

When Amazon is the chief disruptor, the odds are stacked against you

Any company that comes along trying to reinvent book publishing is competing not only with traditional book publishers but also with Amazon(s AMZN), which is almost 20 years old but keeps finding new ways to shake things up. Print book buying continues to move online and Amazon, which is now delivering on Sundays and offering same-day delivery in a growing number of cities, has a lock on that business. Kindle, launched in 2007, is the dominant ebook reading platform and Amazon is continually rolling out improvements to the Kindle…