@Emilia42 Yes, I guess that is true. I was surely surprised when I got an email congratulating me on acheiving Superhost early on in my hosting career (I actually hadn't even heard of the Superhost designation and didn't know what it meant at that point).
But just because guests don't bother to leave reviews doesn't mean the host and accomodation isn't great, we can't force guests to leave reviews so I don't think that Superhost should rest on that. The other Superhost criteria, like not cancelling, responding to inquiries and requests in a timely fashion, not declining any or many requests would seem to me a good indicator of whether a host was attentive to guests more so than if they got 5* reviews from all their guests, since we know that many guests don't really understand the review system, or will give low stars because they were called out on breaking house rules, etc.
And I tend to think that if the place or host was truly unacceptable in some way, guests would tend to leave a bad review, rather than not review. It seems, from my reading on these forums, that it's more the satisfied guests, who tell the host they really enjoyed their stay, and maybe wrote a glowing comment in the Guest Book, who tend not to bother to leave reviews.
And there are many places where the viable hosting season is quite short, like mine- I really only get bookings from late November though April, with a few in the off-season, plus most of my bookings are for a week or two, so a couple of quarters in the past 3 years, I've just squeaked by with 10 stays