The 1970s Phreaking Subculture That Gave Us Steve Jobs - Before Jobs and Steve Wozniak invented Apple, they hacked phones. Slate.com

Wear on the components? What are you smoking today? They cant guarantee ANY wear on the components, if you play 3D games all day long it puts a lot more stress than using a rooted/jailbroken file manager app. The only real factor of wear on electronics is heat, and that is produced by plenty of App Store apps (games, video, etc). The only other thing is memory writes, as Flash memory can only take so much read/write cycles before it cant be written anymore reliably, but again, you dont have to have custom jailbroken software to write the memory to death when you could use anything from the App Store that works the memory (copy files back and forth from iTunes even, whatever does the trick). The main issue with warranty is having to do customer support on a phone that may not be running software that they can reproduce the issues on. If customer is running $uP3R 1337 AW3S03M R0M from some script kiddy developer on a forum somewhere, Apple has no way to guarantee the problem is actually being caused by Apple software and dont want to pay the extra support costs to try to diagnose issues with non-Apple software that hasnt been properly tested. They also dont want to pay support costs for bricked phones due to ROM flashing or low-level OS modding gone wrong, as a bad ROM flash can leave your phone in a useless, non-booting state. This is a perfectly legitimate reason to not approve warranty repair or replacement, as it is the customers fault that the device isnt working. That said, in general software does not break hardware. A custom ROM should void your software warranty (i.e. "I bricked my phone") but should NOT void your
hardware
warranty (i.e."The display has a big green vertical line down the middle" or "The headphone jack is loose"). These are hardware issues that can happen regardless of what software (if any at all) is on the device. Hardware wear and tear is mostly caused by external factors (jamming the headphones plug in and out too hard, mashing the buttons too hard, dropping the phone and damaging the display, cracking the glass, etc). This policy holds for most manufacturers, who will do warranty replacements or repairs for hardware issues not related to a software problem regardless of whether or not you had a custom ROM/jailbreak/root on your device. Apple Im not too sure. This is not a legitimate reason to void the warranty for software issues, as the software is not part of the problem nor the solution.