IMO, not every Purolator filter that could tear is going to tear depending on what engine it's used on, and how that engine is driven. Could be a lot of the tears we have seen lately are due to being used in cold weather where the oil is thicker than usual.
Thicker oil with a positive displacement oil pump is going to result in more delta-p across the media, and winter use of the filter may be a key contributing factor here ... along with other factors like the media material and the physical spacing of the media. This failure I believe has many factors adding up in the same direction that causes the media to tear.