But you are going to be casting mindflay one way or another. You won’t always have mindblast off cooldown or void torrent or voidform or shadow crash.
What are you going to cast then? Mindflay. And what happens when you get a proc? You either finish the channel and risk munching the proc or interrupt your Mindflay:Insanity channel, lose damage and insanity to not munch a proc.
Either way it’s a loss of damage for a pointless change, and people are justifying it out of spite for Mindflay. In which case, why not take Mind Spike if you hate Mindflay so much?
Why would I want to take affliction, a disaster of a spec after Blizzard slaughtered it out of vengeance for its performance in Legion, and port over defects in shadow that were previously fixed and then undone in DF beta?