Well, I really the Ukraine war is a good example of why infantry is important. If you just Thanos snapped infantry out of existence, this would have been one of the shortest wars in history. Russia has an overwhelming advantage in air, armor, and artillery assets. One of the reasons it's been such a slow slog though is because Ukrainian infantry is dug in like ticks, and occupies places which are difficult to advance upon. In the US army, infantry is called the "queen of battle" because like the chess piece, it can go anywhere. Ironically I think one of the main reasons the US has such an abysmal modern military track record is that it massively under invests in its infantry. I certainly think that if the US had of had a larger infantry force in Afghanistan that wasn't so tied to FOBs, it could have completely locked down some key strategic locations and made it very difficult for the Taliban to operate effectively. If you look at the current war in Israel, one of the reasons Hamas can't just do what the Taliban did is because they're locked down and don't have a lot of freedom of movement. That's not because Israel has a great infantry force, it's because it has more infantry than what's really needed to do this.