I have utterly no intention of doing this, but I do wonder how difficult/dangerous it is.
1) on a taildragger the wheels are ahead of the CoG so lift from the water will increase the pitch of the aircraft creating a stable state.
2) the wheels are below the CoG of the aircraft, so drag will tend to pitch the aircraft down (unstable)
3) to some extent ground effect will help stop the aircraft sinking lower.
Presumably effect 1) predominates at the speeds they fly at, and if you hit the water softly enough there'll be a 'cushion' you have to break through before the water goes high enough (perhaps above the axles) before effect 2) predominates.
So how 'thick' would that imaginary cushion be? How much of a margin would there be between skimming over the surface and going 'kerplunk'? Without knowing that, I have no idea whether these pilots are being reckless or not.