Can't speak for the parent comment. However I can relate. Today I installed Dropbox for my grandfather and their default entry-level free account comes with 2GB, but as soon as you create your account and install the software, they offer to give you 25GB of free space if you add 1 file to your account and you install Dropbox on your mobile.
Not sure if that helps them artificially boost their numbers (by claiming more installed devices), or if they try to get your contacts to get more accounts.
Without being overly familiar with that specific tactic, on the surface I think it is actually much more benign.
Incentivizing users to add their first file and install it on their phone (where it will likely want to slurp up photos, videos, etc. to back them up there) isn't a bad thing IMHO. It drives immediate engagement with the core product experience, and I'd be shocked if they didn't have data saying that people who upload at least one file and have the app installed on their phone convert to paid at some rate above people who don't. Thus, by incentivizing that behavior, they can likely boost conversion rates AND make users happier by getting more familiar with the service. Sounds like a win-win scenario to me. I wonder how many users sign up but don't ever use Dropbox.
I found it an interesting approach to an incentivised tutorial of sorts it's very easy to install Dropbox on your desktop and just forget that it's there. By offering you free storage space by introducing you to features, such as their mobile app, sharing, etc, they're making you curious and interested in what else they have to offer you.
You could call it growth hacking I guess. I think it's an interesting alternative to idk, a weekly "did you know that?" e-mail (e.g. Evernote) or a tooltips-driven tutorial, or Clippy.
In case anyone's looking to participate in this promotion, note that the 25GB space is only valid for one year. [1] I looked it up because 25GB is more space than the quota of my years-old free account which has participated in a bunch of promotions.
Not sure if that helps them artificially boost their numbers (by claiming more installed devices), or if they try to get your contacts to get more accounts.