is there "any" validity to the recommended 1g / lb (0.45kg) of bodyweight Protein intake.. that you've come across?
Marketing BS, repeated ad infinitum until everyone thinks it's gospel. The only way you'd need close to that amount of protein intake is if you were on a gram of test a week, and even then you get guys like Mariusz Pudzianowski who's diet is 90% chocolate (he takes supplements due to his Met-RX endorsements, but that's hardly going to be why he's huge).
Assuming your training, sleeping is perfect, you're getting a calorie surplus, you have reasonable genetics, etc. - best case scenario, training naturally, and assuming you're currently in an untrained state you're looking at maybe gaining a half pound a week maximum, and maybe half of that as muscle (these are optimistic estimates). So that's around 15g of muscle a day, and considering the majority of the stuff you eat - including crap like noodles, bread, etc. all contain protein - as long as you're eating some concentrated source of high-BV, reasonably complete profile protein like say a couple eggs, a glass of milk, or a chicken breast then you're already getting the maximum amount of protein your body can utilise, and supplementing with powders is pointless.