Academia.edu is an e.g. of network effects trumping poor web design
Its an intriguingly poorly constructed website, and probably makes a case for the argument that the tool itself only need be good enough for network effects to generate value to end users, and therefore growth in its population. I know I've signed up in particular because it's now seen as the place you need to have a profile in order to be findable as an early stage academic. And there was definitely a need for this sort of tool: previously communities were organically growing around such things as the Zotero and Mandeley referencing tools. Indeed, LinkedIn, the big candidate for online professional networking doesn't appear to specialise towards the academy enough to be used; I say "appear" with consideration, as to be honest it does a better job in some ways than Academia.edu. Putting to one side the old refrain of lack of regionalisation, whereby it should almost exclusively be rendered "postgraduate", Academia.edu's bland option of "graduate student" as user's academic position is not fit for purpose: there is a great deal of difference between the titles MA, MPhil and PhD, and that's just the one's relevant to the Arts.
Also it took me three attempts to remove my automatically imported Facebook profile picture, followed by four attempts (and downscaling the resolution myself on my local PC) for me to get a new one to show. No error message given. Not an inspiring experience.
I guess, as I glossed past above, Academia.edu is likely to be a case of not what you use but who you use to connect with. Not sure that will catch on as a saying however(!)
And so, ta-da!: