[apefish]

The short version of my answer would be "any rules or non rules that make it easier for a player/s to exert undue influence over a tournament outcome regardless of their intentions are probably bad for the game."

A benign example would be a bubble situation where showing a card and annoucing your actual holding heads up is the only reason your opponent properly folds where he would have otherwise busted.
The tangible person hurt by those actions is the person who ends up bubbling. But the layers of harm to the actual outcome of the tourney go deeper.
Assuming it was without malevolence- say I decided to be sporting to Snowball on the bubble because i liked the table banter or something- I now have influenced the outcome of the tournament where I wasn't able to beforehand.

Now realize that allowing those actions in any heads up pot legitimizes any open collusion/soft playing or malevolence that way.