Not all links count equally. Relevance to your subject, the linking page's own authority, its editorial nature and where the link sits in the content all matter more than raw volume. One editorially given link from a publication that genuinely covers your field outperforms dozens of directory or footer links, and the gap has widened as engines have got better at discounting the cheap ones.
Referring domains matter more than link count: fifty links from one site are worth far less than fifty links from fifty sites. That is why link reports should be read by domain, and why a sudden spike of links from a single source is more often a negative SEO artefact or an aggregator scrape than a win.