Polo Rules

The main problem with reffing is the idea that everything is an accident and that everyone is playing with the best intentions.

Whilst this is often true for throw-ins, it's rarely true in a competitive game. We should put more pressure on refs to make calls (of any kind) and not give them the safety net of "well, they probably didn't mean it" – which whilst perhaps being true...

You've nailed it with the first bit.
With regards to the "safety net" bit, it is NOT TRUE. The rules (NAH v4.1) are clear on this. The first clause of the penalties section is:

§6.1 – Severity of Infraction
§6.1.1 – It is the responsibility of the referee to assess the severity of any infraction listed in §7 – §10 and issue a penalty that rectifies the disadvantage created by the fouling team. (My emphasis)

If a team has been put at a disadvantage, this should be rectified.

There is no requirement to assess whether or not the fouling team meant it or not, with a very limited number of exceptions:

There are two rules that require the referee to assess intent:

• §4.8 – Shifted Goal Position (and sub-clauses thereof)
  

• §7.1.1.3 – A player intentionally scoops or throws the ball out of play
  In addition to these two instances, there is also:

• §8.3.1.2 – Incidental bike–on–bike contact is contact that doesn’t affect play and is not dangerous. (My emphasis)
  This last one doesn't really come into the intent category, as the qualifying criteria is whether or not it affects play, i.e. creates a disadvantage for one or both teams.

That's it. Any ref using the "well, they probably didn't mean it" cop-out is not fit to be reffing.
Any suggestion that players should be more flagrant and intentional in their foul play strikes me as a very dangerous route to go down.