RankBrain can have an impact on your keywords campaigns. When you are defining your keywords, you are looking for relevant terms that respond to customers queries. This is how a successful SEO strategy works. And logically, if you are picking keywords your audience is not searching for, you campaign will have no chance to succeed. This is where RankBrain can play a role.
Remember when you used to rely solely on search engines for traffic? Remember when you worked on SEO and lived and died by your placement in Google? Were you #1? Assured success. Well, okay, maybe not assured. Success only came if the keywords were relevant to your site users, but it was the only real roadmap to generating site traffic and revenue.