How is this Relevant from just sliding the Resource of Availability of Metal & Copper During the Map Generation at the beginning of the game? Can't we just manipulate that ? rather than getting an extra mod to increase Loading time and possible conflict with other mods?

Good questions.

The core idea of this mod is "What if instead of having to manage three 'material' resources you only needed iron".

By material resource I mean ores you use to make more factory and create science packs (rather than being used for fuel/power).

With that idea, this mod goes into each recipe, finds any copper and stone related ingredients, and changes that ingredient to the iron equivalent.

After these updates, you no longer need copper and stone at all on the map. They can't be used for anything and really are just an eye sore. So this mod goes ahead and removes their sliders in the new game menu and prevents them from being placed on the map.

To answer your question, just manipulating the sliders isn't enough, copper and stone would still be required to build electronic chips, assemblers, etc. and copper and stone would still get placed on the map. To accomplish the idea I mentioned extra code is required.

The load time hit actually doesn't seem too bad with this mod.

As for conflicts, that is very much a possibility. I consider this mod to fall in the 'Overhaul' category because it makes large sweeping changes.

Speaking of changes, it doesn't make the product iron-related. For example, Void Miners require Iron Ore (with this mod) to make Iron Ore, Copper ore (which shouldn't exist), wood, and fish. The burner stone miner makes stone (which also shouldn't exist).

Yes you are right, this mod doesn't remove copper and stone as products of recipes. I'll add it as a todo. I'm on a modding hiatus for a bit, but this would be a nice change for general compatibility.