You can't become a full stack dev in a year from scratch anymore than you can become a neuro surgeon in a year.
You have to become qualified by an accredited school to become a neurosurgeon by law, which takes years, over ten years of intensive study and practice, so you don't kill people and stuff?
You can become a full stack dev in a year, and don't have to 'prove' anything by law. Not saying you will be the best but you can get good, but the real question is who codes vanilla these days all the time? The way you're making it out makes it seem like that's the case!