A rogue actor may create a new distro, maybe for some niche use case such as accessibility or retro gaming. After acquiring enough false (and even some real) users that the Linux Foundation accepts them as a notifiable distro maintainer, this maintainer could then pwn machines before the exploit is made public.
Are you implying it requires expertise to figure out the ten (plus or minus a factor of two) biggest distros? I think most people that understand the context of the question can figure out pretty similar lists.