"SME" is short for "subject matter expert". Requirements analysts and product managers often speak of interviewing SMEs. Should product managers interview SMEs?
Probably. It depends on the "subject matter".
Is the subject matter the situation and problems that prospective customers face? To document the requirements for a product, product managers need to understand this subject matter. Prospective customers are experts on their situations and problems. They may also be experts in the domain in which they work. It is essential that product managers interview them.
However, prospective customers are not necessarily experts in the technologies that are part of solving those problems. Unless your product manager delves into product design (as opposed to pure requirements), such expertise is helpful to a product manager but not essential.