Well, they are. Players don't need to know as many rules as D&D and they work in a predictable way. There's a reason CoC is played by an entire audience who don't play other RPGs in Japan, for example.
I would suggest that actually a pretty large number of RPGs are more approachable and accessible than D&D, even when we look at how limited the "up-front" learning for D&D is.
In fact, PbtA/FitD games and similar, are, for people truly new to RPGs significantly easier to learn, in my experience. The people who struggle are those familiar with other RPGs and who have difficulty adopting the approach described, but if that's the approach you start with, it's easy.
To me that's a distinction without a difference.
And not letting you knock people out or one-shot them means you can't do "spy missions", so clearly that's a problem even from that perspective.