In common parlance, yes -- because there is no practical distinction. But in cases where something is just using the Linux kernel without GNU and other common userpand components (and there is a practical distinction) then it's definitionally untrue to say that it's "not Linux" if you really meant to say "it's not GNU/Linux".
Alpine Linux is not using GNU. I'm sure there are others. No definition you can ever come up with will have no exceptions in widespread use. Live with it.
In common parlance, yes -- because there is no practical distinction. But in cases where something is just using the Linux kernel without GNU and other common userpand components (and there is a practical distinction) then it's definitionally untrue to say that it's "not Linux" if you really meant to say "it's not GNU/Linux".
Alpine Linux is not using GNU. I'm sure there are others. No definition you can ever come up with will have no exceptions in widespread use. Live with it.