Every application needs to make assumptions about its users, and for some people those assumptions will inevitably be wrong. Why is it, though, that so many social networks and other social applications assume that all social web users are not yet old enough to drink?

That’s the first impression I got from Yahoo’s new social network Mash. It has a clean design, slick ajax, and generally gave me a user friendly feeling, but it also bothers me that Mash thinks I’m a teenager interested in expressing all the quirkiness that makes me UNIQUE:

On Mash, it’s all about play — no work life for you! Ironic for me, since everyone in my Gmail address book on Mash is a media/tech professional checking out the new service.

This is similar to the assumptions that Facebook makes about how we know people:

This is not a critique on Mash’s features, which seem like they’re on the right track for a service still early in its development — it’s an issue of tone. Mash apparently allows your friends to edit your profile if you give them permission, which could be fun, if you want to use Mash for messing around.

The problem is that there are too many one-size-fits-all social networks for having fun and socializing. Yahoo has millions of users, and will probably be able to draw a lot of those in to play around with Mash — with the emphasis on PLAY.

I’m not saying play isn’t a good thing (unless you’re doing too much of it on company time), but all play and no work will make a lot of people over 25 wonder why they need one more playground.

Or maybe this is the way to all web services talk to us now:

Customize this page by adding cool stuff!

Cool stuff indeed.

UPDATE

I just discovered that Mash has introduced an innovative way to distinguish among your friends — you can have “friends” and “BEST friends”:

BFF!