#3. One year anniversary
WWE has a weird thing about anniversaries and this year's SummerSlam marks one year since The Fiend had a debut match in WWE. With that being said and the narrative of The Fiend chasing his coveted title, it makes sense for WWE to crown him champion again where his story began.
Of course WWE could have just done this at Backlash or even at Extreme Rules, but it probably wouldn't have held the same significance as it will if he wins at SummerSlam where everything began. It also is a great way for WWE to get fans invested into the fall months of the year, which is always an added bonus.
In the end, it just makes perfect sense for The Fiend's story to come full circle at SummerSlam and that seems to be what WWE is planning. Either that or arguably one of the most controversial finishes in WWE history, which won't do them any favors as they navigate the troubling waters ahead.