The barrier is actually quite high. Sure, its easy to make a CRUD app that would aggregate ratings. The difficult part is to get people to use it instead of the

The barrier is actually quite high. Sure, its easy to make a CRUD app that would aggregate ratings. The difficult part is to get people to use it instead of the leader. These are called network effects, and they are very hard to break. This is why big social media sites have such high valuations. Any small group could develop an alternative to Facebook. However, the chances of that usurping them is almost zero. The same goes for Goodreads.