For Google, missing the online storage and syncing market would be as damaging as missing social networking: much of the personal information that is most important to its users would sit on some other company's servers, beyond the reach of its search crawlers.
That makes Google Drive its most important new service since Google+. Due to all the anticipation, Tuesday's launch of Drive felt like something of a letdown. Knowing it was coming, Dropbox was able to announce an extension of its rival service and Microsoft came up with new pricing for SkyDrive.
Much of the attention in advance was on why Google has been so late to this market (when I asked Google's Sundar Pichai about that, he said it was due the technical complexity of bringing in all of the different file types Google has added to the service.)
But the sense of anti-climax shouldn't detract from the significance of the move â€“ or the strong hand that Google has to play here.
When it comes to storing, indexing and searching data, Google has a lot going for it. Giving its users the power both to access and search through all their personal information and files â€“ including across all their devices and on other online services â€“ would be a hard act for others to match.
Google is not yet in a position to offer this. Much will depend on the platform strategy around Drive: Can it attract enough developers to build on top of the service, turning Drive into the "back end" for a wider range of online activity?
One challenge will be to convince developers that they are comfortable working with Google and not in direct competition with the company's own applications. Mr Pichai's response: Drive "gives the reach of Google users" to third-party applications, which should be a powerful lure.
Another question is whether Google has made Drive simple and intuitive enough to catch on with users who already have plenty of alternatives. Unlike Dropbox, which has always been able to present a very simple face to its service (even adding a single new feature, as it did this week with a new sharing capability, is done very carefully) , Drive starts out with ambitious goals from day one.
At heart, though, Drive is an obvious add-on to Google's other services. It is easy to imagine, as Mr Pichai says, adding a feature that turns all Gmail attachments into documents in Drive.
Unlike other add-ons "the failed Buzz social network springs to mind â€“ this one at least does not feel extraneous to the world Google already inhabits.