This wasn't just my observation. It was made at both tables at last nite's Games That Can Not Be Named.
Torture comes up repeatedly, because there is no system in game for PCs to extract information from captured adversaries. Most DMs don't want their now prisoner NPCs to divulge too much info. PCs want all info. Frustrations leads to torture.
Fire. Either the PCs are using burning oil, or their adversaries learned from the previous session and are using it on them. At low levels, effective use of burning oil can be a game changer. Either that, or we have a lot of suppressed pyromaniacs playing D&D ;)
As for torture, that might be a good RPG supplement for someone to write. Kinda like a flow chart / resolution table, so we can get away from the descriptions of failed torture for info in our gaming sessions.
Just some thoughts.