Long tail keywords are another bit of scam artist bull typical of what SEO-tards will tell you; partly because it works for the purpose of "magical perfect match" rankings, that quite often have absolutely nothing to do with what people are ACTUALLY searching for.
It's part of the whole "keywords research" hoodoo-voodoo, said particular brand of manure being that if you pick some perfect match phrase that nobody else has on their sites, or isn't even relevant to your topic, put it on a site, OF COURSE it will be in the #1 ranking spot; that's because every other site that comes up is likely a 'non-competing competitor'.
Non-competing competitors is a '80's term for when marketing scammers would use companies not even in the same field for comparisons of success; Look, our auto repair business is more successful than the local bakery... Doesn't make any sense, but if you word it properly, throw in a few infographics filled with card stacking and glittering generalities, and suddenly people are dumb enough to open up the wallet for vague promises.
In that same way, your typical snake oil doctor SEO "expert" uses long tail and obscure word combinations to come up with phrases that you CAN quickly rank very highly for -- I won't even argue that; you pick an obscure combination of words or a really long phrase that nobody else has a perfect match for, OF COURSE it's going to show up high in the engines. It's called a "magic match".
That doesn't mean it will actually generate traffic or that ANYONE is actually typing that search into browsers looking for what your site is ACTUALLY about... and that's the LIE of it, and how the sleazy, scummy, dirtbags who have turned SEO into a cottage industry use it to drain the wallets of those who don't know any better.
Ranking #1 on the search engines for a term nobody is searching for means nothing; ranking #1 on the search engines for a term that has little if anything to do with the content of your site, just means any traffic that does show up is going to be a bunch of bounces -- and annoyed users.
About... five or six years ago on a now defunct tech forums I had a go-around with a particularly ignorant SEO-tard; he was always using "magic matches" that had nothing to do with the topics of his sites as examples of how great his fairy tale bull was. An example was a Photoshop plugin that instead of calling it a Photoshop Plugin, he had put together two words that had absolutely nothing to do with the topic, and then bragged about how he was number one for that term.
Which probably would have meant something if every other site on the first ten SERP's weren't about powder-coating automotive engines... which is why that "magic match" was absolutely worthless -- the odds of anyone typing in that perfect phrase when looking for what the site was about was zero; even if people were searching for that phrase. note I used SERP for what it actually means, search engine results PAGE, as in the ENTIRE page of results, not just one listing on it. Most SEO "experts" don't even seem to know that either and mis-use the term all the time!
"long tail keywords" CAN be a valid technique on-topic with research to see not only if people are using that search, but also that the results on your site is actually what people are searching for... but really if you are writing in natural language about the topic your site is about, IT SHOULD ALREADY BE THERE!
Hence why 99.99% of the time some SEO "expert" uses the term, they're just trying to pack you so full of sand you could change your name to Sahara.