I've never heard this, could you provide some sort of evidence of this? I was always under the impression that warranties were purely manufacturer defined and could be voided for any reason the manufacturer stated up front.
"Warrantors cannot require that only branded parts be used with the product in order to retain the warranty.[7] This is commonly referred to as the "tie-in sales" provisions,[8] and is frequently mentioned in the context of third-party computer parts, such as memory and hard drives." [Wikipedia]
Edit: Additionally, the onus is on the manufacturer to prove that a non-OEM part or service was the proximal cause of a warrantied failure. They don't get to put it back on you without proving their case.
[1] https://en.wikipedia.org/wiki/Magnuson%E2%80%93Moss_Warranty...