Perhaps because spherical bearings are a wear item, sacrificial, and they timeout after period. Knowing the p/n for the spherical bearing could be a good thing.. Have a spare set it the tool box.... you know, for when you nut and bolt a car and find excess play in a suspension bearing....
We installed a set of spherical banana arm bushings in a car a few years ago... from a "reputable" supplier.....they lasted less than one track season... We tracked it down to the the banana arm bushings when we tried to align the car..... no joy....
Popped out the insert and ordered new from Coast.....
And really.... its pretty easy to reverse engineer many of these type aftermarket products....