I would venture to guess that the reason there are so many new accounts that don't become active is because Steemit is not what they expected. Even if they are into crypocurrency, this site can be rather confusing. A lot of people just don't want to invest the time to learn about it. They think it's just a blogging site. When they learn more, they either get overwhelmed or quickly disinterested.
I'm new and find it fascinating. I think it's brilliant. It brings together techy folks with all kinds of bloggers. You can blog about anything that suits your fancy and be among some of the smartest mathematical geniuses on the planet at the same time. You co-mingle in the same environment. Smart platform decision on the part of Steemit.
I'm not a tech geek by any means, but I know just enough to be very interested in where this site is going.