AntiStateQuixote
Enemy of the State
It is almost as if the aim is to create a sensation of threat ("Oh no, I'm slowed, I might get turned to stone") without much danger of the threat actually appearing and taking a PC out of the game.
Sounds like you are exactly describing the "slow burn" effect that mearls talks about here.
The threat of being turned to stone is effective, exciting and fun. The reality of a PC being turned to stone and the "unfun" of dealing with that aftermath takes away from a particular (preferred my many?) style of play.