In a nutshell: high firerate, large mag, and zero recoil (can be negative).
Stats wise in ttk (based on path).
It is the second worst lmg overall in ttk after the Hades, the Holger is even better than it in ttk and the PKM takes a dump on this gun in close range ttk.
But what makes it so op is probably because of it having zero recoil, the lowest of all lmgs. The Bizon of LMGs.
And how it is extremely less punishing and has a consistently or relatively high ttk (especially at mid to long ranges) with its astronomically high fire rate which also makes missed shots the least punishing of all the guns in the entire game.
And how other perks like Disable still apply to this gun. It excels in all ranges so much it is crazy.
So to summarize: Why have 3-4 different loadouts for all ranges, if there is a gun that excels at all ranges?
The only situations where you might lose with the MG42 is against a prefire, mid range gunfight with a DRH and HVK, or a jumpscare and panic hipfire instead of slide-aim, slowest sprint to fire among all lmgs.
As a meta. It is a bad one, but not an Akimbo Fennec or MX9 Meta. It is not so dominant that it is the only option. Like the CBR4 case. And while it is the best gun in the game rn. Guns that are catered to or are the prime specimens for certain ranges will outgun and beat this lmg.
Close Range (0-15m)
Fennec, CX9, Shotties and QXR > Mg42
Mid Range (15m-35m)
HVK, DRH > Mg42 (but this is assuming skill issue incident happens, where you miss all your shots)
Long Range (40m+)
Snipers > Mg42 (why bother bruh?)