I just don't think there's an MMG problem. Yes, there's issues with people camping in rubble and using MMGs, but camping is inherently a problem with Battlefield full stop and I don't know if there's a solution without disrupting the game design and map objectives to deter camping and transforming the metagame into something Battlefield isn't known for. I think we need to be careful when we criticise metagame in games like Battlefield that we're not just complaining about a style of play that is valid, just because it annoys us and disrupts our own. It's like when people whine about classes not being about to do X or Y, when uniformity between classes is not only extremely difficult but basically makes having classes redundant. Strengths/weaknesses to loadouts, classes, and style of play is the entire point of a game like Battlefield. Players need to play to their strengths, not their weaknesses, and accept when they've been bested or haphazardly handled a situation.
With MMGs and camping the core issue is in the visual busyness and asset density of maps, visibility of players, and accuracy of the guns. All combined it creates scenarios where campers aren't so much carefully defending, as exploiting the terrain to clip through objects or remain so obscured and hidden that they have an advantage not through strategic use of game systems but exploitation. And contributing to this problem is Battlefield V's incoherent design, where it doesn't know if it wants to be an arcade run and gun shooter or a hardcore military sim.
I don't mind LevelCap, I just find his criticisms of the game too frequently drop into the former observation; upset the game he's playing doesn't fully accommodate or compliment his specific style of play with little consideration for the broader strokes of a Battlefield Conquest sandbox environment. He's notorious for whining about tanks for this exact reason, because it disrupts his Call of Duty run-and-gun kill streaks and they're too hard to kill and annoying and other bullshit. It's no surprise his suggestions for the MMGs steer it away from being a defensive weapon with limited mobility. His idea of Battlefield is constant infantry focused run-and-gun play, and the reality is this isn't Battlefield no matter how much he likes it. The usefulness of defensive play in Conquest is evident when one team is doing it and the other is not. It's part of the formula.
But yeah, I just don't think there's an inherent MMG problem. Almost all of Battlefield V's balance problems tie back to other issues. MMGs a problem because of bipods? No, it's because of the damage model, player visibility, and cluttered level design. It's like saying high powered snipers are a problem, because the approach for these players is exactly the same as MMG camping; camp with a high powered rifle, only over an even longer distances, and pick off targets. The issue isn't the rifles, nor the class. The issue is the flat, open topography of most of the maps making this role too easy and flexible to play.
"Tanks are too powerful in Battlefield 1". They weren't, ever. Players just fucking sucked at trying to kill them.