Because LWGJL is a Java wrapper around an implementation of OpenGL
written in C, which is not object oriented.
You can find this in the LWGJL wiki:
Libraries like OpenGL, OpenCL and OpenAL are written in C and hence
static in nature. As LWJGL is designed to be as simple and as close to
the metal as possible its API is almost entirely static to allows it
to match as closely as possible to them.