Also characters are scavengers, not scientists with a master's degree in engineering and chemistry.
Maybe you.
In this world it is enough good knowledge source to allow learning so high technology. (Enclave, BoS, VC, NCR, Shi,Gun runners,Ghouls from Gecko(?)). And don't talk they protect they knowledge and don't share it with others. People can learn. If you get enough oportunities to broke something you can realise how it is made.
First problem is that now every character can craft plasma riffle even if it is an completly idiot., but making some higher requirments will not change anything. People just make alts only for crafting. Nothing to do with that unfortunatelly.
Second problem is resources to make high trier stuff are too easy to get in high amount. They just should require some rare ingreedients not so easy to farm/gather, but still accesible to normal peoples.
And that propably will be fixed(read first post in that thread).
And maybe there should be cooldown for crafting. Making 50 CA in 1 minute is ridicolous:)