Those engines serve a different purpose than a library like Raylib. They give you a bunch of stuff out of the box like lighting, raytracing (esp Unreal), pathfinding, and a ton of helper functions used in making a game like vector calculations.

Raylib helps you draw stuff, play sound, and do the basics. But you're gonna be writing your own lighting/raytrace/pathfind/etc functions and it's ultimately going to take longer. The upside is if you need to do something very unique, all of the power to mske it reality is in your hands because Raylib isn't opinionated on how your game logic works and how it's packaged up. It's just the delivery guy to give the result to the user.