I worked at a computer store in college, and we got several that were hit by surges usually during storms. Typically the power supply would be dead (MOV inside would blow), or the modem no dial tone as people would plug their power into a surge protector but plug the modem straight into the wall and it would take a hit, usually that's due to electrical storms.
During bad electrical storms it wasn't unusual to see burned components, sometimes blown right off the board (modem).
We had a burn in policy, any computer we fixed we plugged in and ran diags for 48 hours. So we might get one that won't power on and replace the power supply and sit it on the rack to run and if it passed that burn in test then it was probably just a bad supply. But if something else died during that burn in that was a sign of a surge. We would replace a second part and something else would fail. What happens is surges will get through and stress other components to where they fail shortly afterward.
So we had a form letter where it something like "I <techname> working for <computer builder> have diagnosed this computer and based on symptoms and experience have determined that it was damaged bu an electrical surge. Based on previous experience it is our recommendation that the complete system be replaced rather than repaired.
APC and Tripp Lite and Homeowners insurance usually always replaced the systems that I recall, I don't remember any disputing it.

Somewhat related, the only vendors I ever had issues with for warranty stuff was Sony, Microsoft, and Apple, they would fight every step of the way while other companies were usually pretty good about taking a computer stores warranty returns.