#4 To protect Brock Lesnar, The Fiend, and Adam Cole

One of the major reasons why the company may have gone against the Survivor Series tradition is because of the complicated booking a match between the top three Champions of the company might bring.
We will witness the three top female Champions, namely Becky Lynch, Bayley, and Shayna Baszler compete at Survivor Series, but picking a winner between them is tough already.
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When it comes to men, things get even more complicated as the company has built all three men as the absolute best in the business.
Brock Lesnar is a man who has only been defeated by a handful of men and keeps getting more and more dominant with each outing. ‘The Fiend’ Bray Wyatt is new to the mix but has proven to be the most lethal force in WWE through his recent antics. Adam Cole has been one of the best athletes in the company, and recently defeated former WWE Champion Daniel Bryan and came close to defeating former Universal Champion Seth Rollins.
Therefore, picking a clear winner from these three men would have been tough and would have left many fans unhappy in the process.
Instead, putting the WWE Championship on the line against a man who has already got a storyline building with Lesnar makes more sense, and frees up Adam Cole to either captain Team NXT or get into another match for the event.