When people say “I’m using only C++ for my game”, they just mean their core game logic(entities, etc) are written in C++ and they are trying to limit the amount of blueprints they actually use. The editor is still used to create new levels, add objects to that level, etc. Blueprints are still needed for animations and simple scripting, you just keep the “heavy lifting” (e.g. entirely new functionality) in C++ as much as possible.