#3. A quick replacement without any need for a storyline

As we know, once WrestleMania 36 officially shifted to the WWE Performance Center, the company started putting in less effort into making it the biggest show of the year. The original WrestleMania 36 card was impressive in itself, but a lot of changes had to be made due to the circumstances.
We don't blame WWE for taking their foot off the gas in terms of the build to WrestleMania since the biggest show of the year can't be in front of an empty crowd. We imagine that they will double-down on making SummerSlam a great card should the crowds return by then (which we fully expect them to).
Look who just shut down all of Tony Khan's critics! More HERE.
But given that Roman Reigns was replaced before last week's episode of SmackDown and WWE chose to advertise the match anyway, it becomes confusing as to what the thinking behind it is.
Either way, there's no doubt that Strowman was an easy option to go with and a superstar they could use without needing an actual build.