Paolini is just blatantly copying the idea from his idol Brandon Sanderson.

Except that Cosmere was built up for decades within his novels before it was announced as an overarching universe, to the point that fans had figured it out long before Sanderson said anything about it. He waited until he knew he had a big enough fanbase to support such a huge project.

Paplini annoubced his fractalverse literally begore the first book came out, with no idea of how it would be received or whether there would be enough interest to sustain an expansive multi-novel universe like that.