In Halo CE, you could use custom game settings to change what weapons spawned on the map from various pre-sets. So you could make every weapon a rocketlauncher, or shotgun, or reduce it to close-quarter weapons only.
But we have a lot more weapon spawning mechanisms in Infinite, from weapon racks, native weapon spawns, drop-pods.
blanket replacing every weapon with a single type would be "easy" to set up but also pretty worthless since we have better control of everyone's spawning weapons in modern custom game settings.
It would be awesome to have such presets like:
"Make everything banished/ forerunner/ unsc weapons",
and map a given weapon spawn to a different one based on their class (snipers are: s7, shock rifle, stalker, skewer).
or make everything heavy, so only launchers, rockets, melee, snipers on the map;
or make everything light, so none of those.
You can see how making the decision for what to replace and when would be super hard to blanket apply to everything in the map, without completely breaking whatever balance the map had.
Something that WOULD be neat in the custom settings is:
specifying which of the two spawn options the weapon racks would pick, at the level of picking between each possible pair.
This entire rant is to say that: adjusting weapon spawns on the map really is better suited for Forge, even if it means making a whole copy of the map, and copy protections break that.