#2. There's no other viable contender for Brock Lesnar on RAW
Brock Lesnar finds himself in a bit of a dilemma. For the first time in a few years, he has no challengers for the WWE Championship, which is why he's entering the Royal Rumble match - at #1 on top of that.
The expectation is that he won't win and the superstar to eliminate him will be the one to face him at WrestleMania 36. The reality is that WWE doesn't have many opponents that can legitimately challenge him for the title. They can't go with Seth Rollins again since it would be a repetition of 2019. They certainly can't do Roman Reigns because he's on SmackDown and again, that would be repetition.
When looking at the fresh stars that are being pushed on RAW (such as Buddy Murphy, Andrade, and Aleister Black), none of them seem ready. The other outside names are Cain Velasquez and Tyson Fury - both of whom are too green at this point.
Moreover, Fury's appearance all depends on whether he beats Deontay Wilder on February 22nd. This leaves Drew McIntyre as the only viable challenger for Brock Lesnar at WrestleMania. He doesn't even need to win the Rumble for that.