It would be useful if all academics should set up a page on Academia.edu. I always urge students to set up their own page; its a good way to become an active part of a wider professional and intellectual community, to make yourself known, and to get access to current research. I won't urge colleagues to use the service, though. Archaeologists can be rather ornery people, and in my experience if you preach to them they will either ignore you or perhaps do the opposite.
But there is one HIGHLY NEGATIVE FEATURE on Academia.edu: Linked co-authors. You post a paper, and then invite your co-authors to link to it. Then the paper is listed with the various coauthors (and their logo and links) on your page. Sounds great doesn't it? The problem is that if your co-authors are NOT members of Academia,edu, then they won't be listed! You can list them in your own custom metadata on the paper, and of course they are listed on the paper itself. But it means that the basic listing for the paper omits authors.
- The listing is incorrect.
- It is unscholarly.
- It violates professional practice, and
- It violates scholarly ethics
Consider an imaginary paper:
"The nugatory puff as a cultural imaginary" by Foucault, Derrida, and Latour.
If only two of these authors are on Academia, the paper will appear like this:
"The nugatory puff as a cultural imaginary" by Derrida and Latour
(assuming Foucault is not a member of Academia.edu). I don't think Foucault will be too pleased, and authors Derrida and Latour should not be happy either, to have their paper inaccurately represented. Unless they are trying deliberately to cut Foucault out of the action........
Academia has at least thought about this, and you can add a non-member as a co-author and they will automatically invite the person to join. But I am not interested in harassing my colleagues to join a service. This is what ResearchGate does, and that is the main reason I resigned from that service.
If Academia.edu is going to portray itself as a scholarly resource, then they must adhere to professional standards and ethics in the way they portray papers.