Exactly and the limits imposed by the ball joint is pretty wide in my opinion you should be easily able to tighten the stabilizers in those limits.
I have a 1740M with the same design approaching 300 hrs with a lot of roading with a 900 lbs snowblower bouncing at the back on a gravel road... no problem so far. Used a box blade and a two row plow in rocky ground too without issues.
I had a John Deere 850 with a rotary cutter - stored inside. The ball rusted inside the 3pt arm, and it broke off about 3" back from the end from metal fatigue. No big deal to weld it back on, but it took a lot to free up that ball. I now spray the balls with penetrating oil now and again.
If you think about it most attachments have a pin mounted the same way as the OP's tractor and they don't seem to fail. That said, if there is a failure it is a lot more costly if a axle housing breaks as opposed top a piece of angle iron bending. It seems like a weak design feature to me.
But is almost certainly not cast iron but cast steel and that is something completely different.That's because almost NONE of the attachments are cast metal where the attachment pin is mounted ! Essentially all are mild steel or some form of steel far less brittle than cast iron.