For one thing, I would honestly choose .50 over mg42 every time given the choice. Faster setup, crazy dps, and really good stock penetration along with sprint and AP rounds. The only reason .50 can be this powerful is because it comes the latest of all nondoctrinal mgs. If .50 was t0 you could literally just spam like 4 and use them like the old maxim (a move to victory). Sure, they'd be a little squishier but they wreck infantry and light vehicles (except for luchs). Comparing .50 to mg42 is silly; the only thing mg42 has over the .50 is a wider arc, which doesn't even matter because the .50 can setup and teardown very fast.
Edit: this is coming from a usf player.
if you are saying MG42 is much better than 50.cal i should say you are totally wrong. Counter of the MG as you know is Flanking in other word MG is nothing when it gets flanked so tell me which one gets Flanked easier ? MG42 that covers Wider Area or 50.cal ?
and about Maxim spam ; People could spam maxim because it was costing 240 manpower while 50.cal costs 280 manpower.
in addition Maxim had 6 squad member while 50.cal has 4 squad member.
even if someone spam 50.cal he will lost map control because he wont be able to take whole map with defensive unit.