The problem is players are often idiots.

Like, they'll just forget key facts.

"We think Bob did the murders!"

"You mean Bob, the accountant, who was with you when the first murder happened and has rock solid alibis for the second?"

"...yes"

"ok. How do you explain those two things?"

"... nevermind "

Or like, "we think he's a shape shifter!"

"So remember in session 0 we established this is a modern day, no magic, realistic setting?"

"...no."

"Ok, well, we did, and it's in the setting document pinned in the channel. Shape shifters don't fall under realistic, modern day, no magic, so they don't exist in this game."

"...oh."