They, and everyone at the time, were kind of forced to switch to lead-free solder by RoHS. At that point, there probably hadn't yet been tests showing the results of constant thermal cycling, so the brittling effect was unknown. Apple was particularly affected as an early adopter because of their PR stance on environmental issues.

Refusing to acknowledge anything was wrong was the real problem. But that's just a reminder that companies don't care about you. Brand loyalty is a quagmire.