why is it impossible to find new small ball joint a-body complete control arms

I have been running a ball joint welded in place for 6 years. It had enough threads to screw in snug, but any pressure just turned and turned. It is tacked at 4 places around the joint. Of course when I need a new one, I'll have to toss the arm, but as least I got another joint's life out of the arm before I did. This has come up before here and there are lots of folks using the same fix.