#3 Never the right stage
There has been a lot of hype around Lashley vs. Lesnar, for many years now. It would have been unfair to give away the dream match on a small stage. It is worthy of only the big four pay-per-views. So, let's look at them one by one, shall we?
SummerSlam was far too soon for Lesnar and Lashley to clash, and it was also the site for Roman Reigns' coronation as the new Universal Champion. Survivor Series pits superstars from two different brands against each other, and Lesnar and Lashley belong to the same brand. The Royal Rumble has not happened yet, and if Strowman loses the match, we would always see Lesnar vs. Lashley take place.
Will Lesnar vs. Lashley clash at WrestleMania 35? It does seem unlikely for now, and WrestleMania 36 somehow seems like a likelier possibility.