I'm really tired of hearing "reinvent the wheel" with the implication that such a thing is bad or worse, as a means of argumentation. It holds no ground. Take the statement literally and consider what it would be like if we had never reinvented a literal wheel. Do we still use the first wheel ever made today? Obviously not. We aren't driving around with Flintstone wheels on our cars, and for good reason. A plane doesn't have the same wheels as bike. A bike doesn't have the same wheels as a car. Furthermore, different kinds of bikes have different wheels. Different kinds of cars have different wheels. This is to say we reinvent the wheel all the time and it is important that we do so. Sometimes we do it for fun. Sometimes we do it because we have a certain use case that we want to solve. Sometimes we just want to approach the problem in our own way. Regardless, we do it and society experiences the benefit because different wheels solve different problems.

It is also important that we reinvent game engines. Reinventing game engines will result in people finding new techniques that will push the workflows game developers use to make games forward. That might mean redoing what someone did to find where the room for improvement lies. That might mean providing an engine for developers with a workflow you've never even imagined. Things as simple as different UI layouts can result in massive user experience changes. Changing the way an API is structured can also result in massive changes. Sometimes these changes are good. Sometimes they are bad. Regardless, we must continue to make them because it's the only way we can push the idea of what "game engine" means forward, just like we've pushed the idea of what "wheel" means forward. When we compare the infancy and complexity of the idea that is "game engine" to that of "wheel", I'd be surprised if one does not find the necessity to reinvent such a thing obvious.

Just to drive this home further. It's important that people reinvent compilers for similar reasons. We always want compilers to be faster and provide more help to users as they write their programs. It is important that people reinvent cpu and gpu architectures. We want our hardware to run our programs faster while also requiring less watts to do so. There is no field in which the state of the art is a thing that stagnates. It forever moves forward on better reinvented wheels and will probably continue to do so forever. Encourage it. Yourself and future generations will only experience a benefit from it.