As I am the person who meets and greets (so to speak) all new members onto WOL, I am very aware of the very large number of new profiles that register and never post even one piece of poetry. Similarly they rarely comment on other poets work either.
I cannot for the life of me understand their reason for enrolling in the first place.

It would be interesting to hear other's views.

I would welcome new poets posting an identifying picture - it could be a location or something else, rather than a picture of themselves, if needs be. As Graham says, it would be good if such shy poets engaged with this site a little more.

Perhaps they’re readers rather than writers?

John's (Coopey) suggestion is a valid one I think. I recall the days when droves of registrations in various online poetry sites was found in school projects and homework for schoolkids to learn about poetry first hand. Very few of these stay on. On the other hand there would be the occasional or periodically silent ones, such as myself - having surges of activity and then become silent for a length of time only to return again, like an erratic tide. It is a strange thing. But that is how I have come to observe this particular phenomenon.