Source? I have only read that 8s are in the minority, from Wisdom of Enneagram.
To entertain that, however; on one hand I can see it, but those individuals might not fit the stereotypical picture of E8. E8 doesn't have to be this great, inspiring, powerful, fear-inducing, ambitious pack leader, sometimes I think they could just be your garden variety bully or useless abusive husband.
Maybe, if they really are that common, we might have had the wrong image/understanding of 8s and how they manifest. Something like the INFJ effect where 8s are described very positively online (their ambition, aggressiveness, leadership) that people who do not possess those are 'automatically not 8s'. Or rather, people who are unable to exert those traits effectively or in a manner the theory describes, are shadowed over as not being 8.
Something like "if you're ISFP, then surely you have artistic interests / can do art!" Their natural inclination makes it that there is much overlap, but not necessarily. In which 8s really might be more common than we think.
Thoughts?