Linkbuilding is an important aspect of SEO, but how many companies go about it could only harm their organic search potential.
Furthermore, SEOs do not come best-equipped for linkbuilding efforts such as engaging in email outreach.
However, an SEO expert can help you to maximize the opportunities of any PR & other digital marketing assets.
For example, this can include redirecting broken pages found externally, addressing redirect chains, ensuring link equity flow throughout all important pages, and so on. Following SEO best practices for ideal landing pages, anchor text, keyword-rich context, and other factors to optimize existing links will help. Competitor research can provide ideas too.
In short, a good SEO does not build links so much as optimize them!