If you are one of these companies, you're the reason I could even get into this space! The company I ended up working for basically would stick 10-15 potential

If you are one of these companies, you're the reason I could even get into this space! The company I ended up working for basically would stick 10-15 potential Junior engineers (majority from bootcamps) in a room for 2 months and give them all 2 identical features to ship. Then access to the dev codebase, docs and the ear of senior engineer. People would help each other, it was expected. People would go learn parts of the stack come back and teach everyone else (this is how I learned about GraphQL). At the end of the 2 months anyone who couldn't preform was let go, everyone else was placed. I understand this was a boomtime thing that only works as massive companies, but it makes getting a new person on your team easier if they know the codebase/workflow. For the new engineer it also really helps to get used to how code works in a massive repo when all you've done is tiny self run projects.