PPC specialist manages advertising campaigns by attracting users to the landing page using paid tools: Google, Facebook, etc. The very concept of a PPC specialist is much broader: it is an expert in contextual advertising who must be able to work with all paid traffic sources.
If a person has expertise in various advertising systems, then his value is much higher than that of a targeted specialist. Agree, it is more profitable for a company to hire one specialist who can work with different advertising systems than to hire several employees.
Professional course suggestions will be provided here - you can explore each link and choose what suits you best!