They can all be open to manipulation. I remember a cricket game back in the old World Series where if NZ couldn't win, then if they lost heavily enough to South Africa, South Africa would get a bonus point and Australia would miss out on the finals, so NZ did a go slow in their chase. Not great sportsmanship, but I could see the same happening in the NRL. And South Africa ended up beating NZ in the finals series, so there was some karma!Why?
In rugby union for example, games can have between four and seven competition points on offer depending on bonus points. The NRL had bonus points in their pre-season tournament this year. Soccer gives 3 competition points out to a winning team, but only one each in the event of a draw. Domestic cricket comps have different numbers of competition points available depending on the result. And I could go on.
The number of competition points awarded in a game isn't some sacrosanct rule that can never be different. Plenty of comps run perfectly fine on that basis. Though I do agree that the best outcome would be just getting rid of golden point altogether.
The thing I like about the 2 points for a win, 1 point for a draw system is it is so simple.