If the weapons from encounters all had 0 deterioration, what would be the point in crafting then?
It would completely ruin the crafting ecenomy (which is already broken IMO).
Weapons gained from encounters should have high deterioration, to force the player to either;
1: fix the gun, to then use it or sell it.
2: if upgradeable, upgrade or sell as is to a crafter who can upgrade it.
3: disassemble for parts to make a new and better gun.
4: trade all the junk guns for one new gun.
High deterioration on guns gained from encounters does, IMO, stimulate the economy a bit. The guys with factions will most likely disassemble/fix/upgrade the guns, while the solo players will trade them around.