I'm an engineer and failure analyst for a heavy equipment manufacturer and this whole lower ball joint issue really interests me. I have no doubts that there are poorly made products on the market that will fail after a very short period in service, but I also believe there are many other factors at play that end up obscuring the true root cause:
1. Lifted vehicles. Strong possibility that the ball joints with stock geometry were never designed for the stress'/angles that people are placing on them by adding lifts. This is already commonly discussed. I know very little of ball joint design other than their basic assembly and operation, so I won't comment any further to avoid speculating.
2. Installer error. After searching multiple threads, I rarely see any comments about this possibility. Even with qualified technicians, workmanship issues are an everyday concern. Now replace that qualified technician with a DIYer like most of us on here, and that risk explodes. Dont get me wrong, I am in no way criticising the good people on these forums. Whether it is a hobby or a necessitiy, working on your 4Runner is a great thing to learn how to do. (I also do not by any means consider myself to be a qualified technician.) Incorrect installation such as misalignment of guide dowels, improper bolt torque, improper lubricant type or quantity, contamination, and many other factors are real world concerns that will cut a ball joint's life in half or less.
I won't offer any advice or try and steer users any one way or another. When in doubt, OEM is the best option when possible. However, the "ONLY OEM HERE IS A LINK" claims seem quite anecdotal. Yes, if you buy a shady LBJ for $15 from amazon/ebay, may God have mercy on you; however, there are other reputable brands. No mainstream automotive parts company wants to design and manufacture a product that will kill its consumers. That is bad buisness.
My biggest reason for this rant is availability. Where I live, OEM LBJs cost in the neighborhood of $400 CAD for one. I cannot justify putting that in my ~$2500 CAD 4Runner and have opted for other brands (namely ACDelco Professional line). If you opt for a reputable brand and are still concerned, check for end play as per the service manual every oil change as susggested by other members.
So when this topic is innevitably brought up again for the 356th time, commenting "ONLY OEM" may be logical for my friends south of the border, but consider adding other constructive thoughts/facts lest there be a lowly Canadian listening in and buying OEM means remortgaging the house.
As an aside, if you are unfortunate enough to have one of yours fail, feel free to message me pics. I don't know what I will be able to determine just from looking at it, but maybe I could see something of value for the community's sake.