Engines don't like even a little bit of water.
Not strictly true, as water injection or water-methanol injection was a very common technique in high performance (mainly military) piston-engine aircraft.
By using water injection, the cooling effect of the water allows the fuel mixture to be run leaner at its maximum power setting without detonating.
I think Step Turn is spot on here, more power, more heat and less fuel - a win-win-win situation!!
FBW