again, personal opinion :-)

HCB chose NOT to involve in the developing phase of photo does not make him a less of a Master. And he's for sure not the only one.

For his subject, theme, way of working, he had the ability of making such choice. For some, it's different. They prefer to influence that part of the process for a desired outcome. And they have the possibility of doing so.

As for credit, many photo journalists sent in their films to the magazine while still on assignment. Do the persons in the dark room deserve the acknowledgement? aboslutely. But their role, again, in this particular stream of photography is not quite on the same level as the photographer him/herself.

Big name fashion designers have assistants to 'finalize, interpret' the sketch.
But do they get their names mention on the runway?...