Most of the bootcampers did three months of "frontend" work and are oblivious to what goes underneath in the murky world of business logic and services.
Until they have been able to demonstrate they are confident in:
* Presenting data to a user
* Validating inputs
* Making correct requests and understanding the interactions of an API (whether its REST, RPC, programmatic, internal)
* Processing requests
* Persistance and access of data
* Basic security
* Be able to document and explain all areas to a basic level.
* Debug and provide a root cause analysis.
Then they will remain a junior developer and I think that will be many of these bootcampers fate, as they are either unwilling or incapable of doing work outside their comfort zone.