Those networks can still track user habits by clicking the URL. In one acorn, they will know they came from your site, any user agent information, screen size (via JS on the social network site), if they are logged in they will associate them going to your site even if they decide not to share the URL.

The only thing they aren't seeing is additional analytic data they're missing out by not having there JS installed on your site, but its still enough data that they can use on there end for targeting advertisements which is what they are using this data for.