From what I saw, the main reason Australia kept swapping players was because it's a friendly match and coaches want to try out different people. It’s honestly the perfect time to give newer or bench players some real game experience. For example, Isabel Gomez made her debut in this Australia vs Argentina game, and that's a big deal for her! Plus, some regular starters might be resting up after a busy season or even saving their energy for more important games coming up, like the Asian Cup qualifiers. Add to that some players picking up minor injuries during the match, like Kahli Johnson leaving after hurting her quad. I think the coach wanted to keep everyone sharp and ready for the actual tough games, not just this friendly. It actually helps the team in the long run by making sure lots of players are used to playing together during real matches, not just in practice.