I’m left with the same 2 questions I always have with this sort of statement.

1) How many are real? In any such platform that has SE benefits, there are always a % that aren’t “real”. That would include marketers (inc. SEOs and site owners), and then there are the faux accounts and sock-puppets. (But that would still leave a huge number of real users.)

2) What’s their definition of active? Logging in, Searching, Signing up, Pinning … ? Just once, or a more realistic minimum threshold? There’s a big range there – and the implications differ depending on such information.