TL is meant to share pictures and learn by looking at and critiquing pictures shared by others as well as learn by receiving critiques yourself.
Now at the same time TL is also meant to be open for everybody. Now it is just a fact that there are not so many pro's on TL, there are a few more skilled amateurs but by far the majority consist of people with less skills. And it is absolutely fine that it is like that.
So to answer your second question, on balance it seems to be more of a sharing site , but it is a wonderful sharing site that depending on how you use it can be a tremendous learning experience for people of all skills and that is exactly what it should be.