1)You are fixating on arbitrary units and completely ignoring game balance.
2)Weapons and tools indeed do wear down and become useless after prolonged use and need to be thrown away or turned into scrap. Weapons and tools wear down and break, and indeed lose mass along the way. You sharpen a knife or sword enough, you end up with a stub, much like sharpening a pencil. That's leaving aside breakage and loss of materials that way. Club and hammer handles break, the heads wear down over time.
3)Again, you are fixating on arbitrary units and completely ignoring game balance.
It's like if you complained about how you get too little meat you get from a pig in game but totally ignored the fact you can grow a new pig in a couple days with a couple carrots.