Maven just hides the complexity in its plugins which are implemented in Java.

If you don't need any plugin - then, yes, it's simple.

But once you need specialized plugins it's no better than gradle/bazel. The latter two lets you add some logic in the build scripts - so at least it's visible to users. If you need special functionality in Maven you have to write a plugin or gather a few plugins. And when it breaks down (as all tools do) -- it's difficult to find the code and understand the problems.