They certainly don't intend to warranty every sludged up heap on the road. Someone with a vehicle with shoddy maintenance is going to have a great deal of difficulty going after a filter manufacturer if something goes south coincidental to a filter failure on a beater, despite the OCI being short or long. Their warranty statement, already linked, states, "This warranty DOES NOT COVER any product that has been subjected to misuse, neglect, negligence or accident, or that has been improperly maintained, operated or installed." The means, to me, no junkers with questionable maintenance issues and no oversizing or undersizing or crosses to a cross to a cross.
The wording of 3,000 miles or OEM interval is on their site. On their PureOne page, it states, "Purolator PureONE oil filters should be replaced every 3,000 miles or 3 months depending on the driving conditions - or unless otherwise specified by the vehicle's manufacturer." The Classic page says nothing about miles. Then again, neither page mentions tears, either.
The 3,000 mile mention might have looked impressive perhaps 40 years ago; now it's just subject to derision. I don't need a filter manufacturer mentioning tiny, historic OCIs. If a filter isn't up for an OEM OCI on a modern vehicle, don't specify it for a modern vehicle.
Why don't they just remind us to adjust or replace our points at every oil change? It's as out of place as that embarrassing 3,000 mile mention.