So what is the deal with "Mirrorless" cameras? One of the most silly ways to describe a product; by something it hasn't got. EFI wasn't called Carb-less after all. I suppose it's the result of "DSLR"s (Digital Single Lens Reflex) being so descriptive... but... really it wasn't all about that. The SLR was just one aspect of the cameras, what was really just as important was the ability to change lenses, focus, change, aperture and shutter speed. "DSLR" is a incomplete term as much as "interchangeable lens camera". But since "DSLR" became accepted "Mirrorless" was one of the obvious counter name.
But what does bother me is there's not a good term to describe mirrorless + DSLR. "Interchangeable Lens" is one of the options sure, but there are interchangeable lens cameras that are not the same. Drones, even phones... Likewise you can get full frame cameras that have full manual control but you can't change the lens. It all makes conversations hard when discussing the pros and cons of mirrorless + DSLRs.