The tips of the blades travel close to the speed of sound. The blades are quite difficult to manufacture as it is, it's a big challenge to add intentional weak points and/or weight by making them foldable.

The tips of fighter aircraft wings travel faster than the speed of sound, deal with far more stress (from turns, explosions, etc.), and the wings I expect are more complex and difficult to manufacture - but they fold.

I'm not saying you are wrong, but by themselves those factors aren't entirely convincing to me.

(Also, the wings need to fold and unfold repeatedly over their lifetime; the blades could just be, in theory, shipped in pieces and then assembled once).

Mega budgets and maintenance schedules.

Fighter aircraft also have a very short lifespan measured in thousands of flight hours and enjoy constant maintenance compared to a wind turbine expected to work 24/7 for decades with minimal maintenance.