The machine gun has been a major force multiplier in infantry combat. Unfortunately many unit leaders do not know how to employ assets like Snipers, Machine Guns, and Indirect fire effectively.
The rise of portable belt fed machine guns pretty much eliminated the tactic of the mass human wave attack. This also allowed for smaller elements to suppress the enemy with fire so other elements could flank.
It drives me nuts when I hear people say that machine guns have no practical use. Besides being fun they are also a cornerstone of modern infantry tactics.