Why do lightning data cables have chips?
These chips are used as part of Apple's MFI Certification program. Basically, you have to be a certified developer to sell lightning cables. 

If you buy a lightning cable from a reseller, you may receive a notification on your iPhone like This accessory is not supported every time you plug in the lightning cable. The pop-up is quite annoying. Your iPhone may then not charge, or charge very briefly, before mysteriously stopping to charge. It is not a hardware issue -- 5 Volts are still being passed through the cable -- it is Apple saying "you need a new cable!"

IMO, Apple also uses this as a kind of planned obsolescence. It is my personal theory that the date of manufacture is also logged alongside the ID stored within the chip. This means that your phone's operating system knows how old the cable you're using to charge it is. So even if the cable is passing 5 volts to the phone, in theory, this would allow the Apple software to deny the voltage, preventing your phone from being charged. In theory, this would require you to spend more money to buy new cables. 

Which, IMO, is the entire point of the MFI certification system - to make people overpay for "certified" cables, and choose when the cables break themselves so people have to buy new cables. Based on my experience, there is no hardware issue at play here, just a company using their monopoly to turn a profit.