Link building is useless if it doesn't add traffic to your site. It may seems good to see one link in your backlink profile but if it doesn't give your site new visitors, then you are not squeezing the most value out of your link building efforts.

Outreach is your first initiatives to increase your site's referral traffic. You let your prospects identify your requests (i.e. content placement) and why you are worthy for such. If they accept your requests, you can submit your content and get a link from that effort (contextual link from your guest post or from an introductory paragraph of your infographic). And from a proper placement of your link, you can receive referral traffic from your prospect's page/site.