>why can't AI-assisted PR reviews make it less tedious?

Godot is a performance critical system in the realm of a million lines of code (?).

Keeping your system both correct AND performant, requires people understand how it works. This kind of technical knowledge is slow to develop, so it's one of the most valuable skills to possess.

I don't see how you continue to understand your system when people are both generating code with AI and using AI to review it's output.