Things like oblique clipping planes for the camera's frustum. Basically something so specific and niche that it's kinda understandable that it's not a focus of the main engine.

Me who programs in rust which has a specific compiler message to tell me what happened

As an avid godot dev, the only gripes that I've had with it are a) merge conflicts can be a nightmare (but you can use git unlike unity sooooooo) and b) it lacks some deep control, but I was just able to fork it and implement it myself lmao.

It's actually really polished imo. It's sleek, minimal (compared to the others in its weight class), only 100mb, and development is just accelerating.

Sounds like an anti trust lawsuit waiting to happen tbh