LMGs are just coming too fast in the game and aren't dictated by any strategy.
In vcoh, lmg42 were locked behind grenadiers and really expensive, like actual pgren with double shreck.
BARs were also locked behind a strategic choice, or you were going garage and a fast m8, or unlocking general BARs.
Today, on a Ostheer vs USF matchup, you got expensive Rifles doing the job vs cheaper Grenadiers until Ostheer reach T2 (so around 5 minutes) and then, if you don't buy BARs, your expensive Rifles are suddenly worthless vs those cheaper grenadiers getting lmg42 upgrade. There isn't anything strategical in the decision making, the game ends around 5 minutes on a LMGs fight or you lose. 1 side get them fast and fuel free, other side for 15 fuel.
USF have a free unit when they tech up, lt is brutal with thompson and bar, paying 15 fuel and 150 mp is kinda acceptable to be able to equip EVERY unit ( hello cheap RE ).
As Ostheer is forced to go T2 kinda fast cause light vehicule ( and the need of lmg 42 ), USF is forced to equip rifleman to be able to continue crushing grens ( or just rifle flamers like 90% of usf player and no need to pay 15 fuel and 150 mp )