I was the source of our metalsmithing system, and your post doesn’t cause me any distress.
The system was created from a combination of my real-world education (metallurgist and mechanical engineer) and research, both real-world (I spoke to several smiths and ferriers and observed/assisted one of them at work for an afternoon) and online. I strove for a degree of realism, and felt that a lack of portability regarding the required equipment made sense.
The smithing system was never really meant to outright replace scavenging for tools, but rather to allow you to create those (metal) things that you just cannot find for whatever reason. I specifically included the ability to create your own anvil, hammer, swages, etc entirely from scratch, so that someone with a welder and a pile of steel and wood could eventually get started from scratch. If you can’t locate a chisel or die set or whatever, check the recipe lists for them; you don’t need a smithing kit to create a smithing kit.
As for alternative tools, it’s an issue of how far can we push verisimilitude before it breaks. A crucible is required because molten steel is ~2500 degrees Fahrenheit; a stone and string vessel will shatter from thermal expansion long before reaching that point. A metalworking chisel is required because a screwdriver is not only the wrong shape, but would break (or partially melt) the first time you attempted to use it to cut hot steel. Swages and dies are forming tools (ClockworkZombie knows their stuff) used to shape the inside and outside of formed steel projects - they poke holes and make stuff round and are used to size and draw metal. Basically, you can’t replace the tools with alternatives because of the extreme conditions they’re subjected to - the same reason you need a proper hammer and proper forge to smith, and can’t fake it with a rock and campfire.
That being said, the metalworking system is an extra layer of crafting possibilities, and it’s hardly something you have to explore with every character. It’s mainly there for the players that really enjoy crafting stuff, and don’t mind devoting the time and resources to it, in order to turn common scrap into useful objects.
