While you are probably right in identifying these two groups as very intense users of such a system, I would argue that they would not be its typical users but

While you are probably right in identifying these two groups as very intense users of such a system, I would argue that they would not be its typical users but rather the people most likely to abuse it. This has to do with the concept of "personal online reputation", which is often used as a weasel word for "stuff people will find when they google you". This, of course, is something you can easily influence and leads to a form of digital masturbation that I am highly critical of. If, otoh, you use a more scientific definition, e.g. "the aggregate of all opinions of other people that have interacted with your previously and that are available in a given social network", this becomes a very interesting measure. And one that is incredibly hard to work with. But, assuming that someone figured out how to handle it, it would be incredibly useful: it would allow for ad-hoc trustful pseudonymous interactions both in situations like the current struggle in Iran, where certain pseudonyms could quickly gather domain-specific reputation and thus become effective gate keepers. The value of such a mechanism extends through all forms of online cooperative services and could be extremely valuable in fighting trolls, griefers etc. Another potential use of this is around privacy: While I believe that we need to find many new (social and legal) norms regarding the handling of personally identifying information in the web, I also think that we will have to develop a generation of post-privacy tools that will help us deal with data that has leaked and will never be re-secured. Creating multi-faceted, rich online identities might be such a tool. These scenarios will be interesting to more users than just marketing professionals and wannabes, although it is likely that the new discipline of reputation corruption will grow right alongside with these tools.