That doesn't make it not a distro, that makes it a different kind of a distro. I'm not sure if we've had ones that absolutely had no package manager, but we've definitely had TONS for which the intent ISN'T installing extra/different software,e.g. a bunch of the specialized raspberry pi ones.
Do you think Linux From Scratch https://www.linuxfromscratch.org/ is a distribution? That project is not a distribution, it helps you build your own distribution. The Linux kernel by itself, although the source and binaries are "distributed" to you (i.e. English-dictionary definition of distribution), is not a distribution.
