offtopic question:

as a recent dabbling reader of introductory popsci content in cryptography, I've been wondering about what are the different segmentation of expert roles in the field?

e.g. in Filippo's blogpost about Age he clarified that he's not a cryptographer but rather a cryptography engineer, is that also what your role is, what are the concrete divisions of labor, and what other related but separate positions exists in the overall landscape?

where is the cutoff point of "don't roll your own crypto" in the different levels of expertise?

You did not ask me, but you should do your due diligence because there are way too many armchair cryptographers around here.