how to implement longtail keywords with smart crawl

Read this article today (https://premium.wpmudev.org/blog/semantic-search/?utm_campaign=Roost&utm_source=Roost&utm_medium=push) and wanted to ask how to implement 'long tail keywords' with Smart Crawl?

Use the 'meta keywords' Smart Crawl feature of each page/post? If so, should I use multiple keywords that are comma separated?

In fact, a tangential question may be why wasn't Smart Crawl offered up as a solution at the end? Very strange to me...