Should SEO be directly linked to Sales ?

SEO has emerged as one of the main requisite for every business and forms the core part of their marketing campaigns. Though most of the SME's have their in-house team working on Digital marketing strategies , bigger companies use a mix of in-house + digital agency working together help building an online presence for them.Also most of you might have also come across ads like 'Guaranteed Top 10 results in Google' promising you to do wonders with your search engine rankings. Be it any of these , linking SEO expenses to the ROI in terms of sales through the website has become part of all ventures.
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As per Brian Dean of Backlinko , there are over 200 factors which are responsible for Google rankings and this is backed by many other Digital marketing Gurus also. Considering this, the basic goal of search engine optimization should be working on those factors so as to give your page ranking a boost for targeted keywords.
I always believed that SEO works for pages and not for websites. You need particular set of keywords for each page for which SEO will be performed i.e tweaking those 200 factors which will help you crawl up.
So logic unfolds like this :

Good SEO = Good Ranking = Good Traffic = Good Sales

Though this sounds great but the issue with most businesses is that they do not know the exact keywords which results in sales. PPC(Pay Per Click) campaigns might work as an good support to SEO and can be used as a testing ground to know the target keywords with good conversion rate and can be replicated in SEO strategy. This might reduce the efforts put in to a certain extent but again the results are not guaranteed.
SEO can be targeted to create awareness about a certain product or to capture leads with help of landing page or in some cases direct sales for the likes of Amazon. So its important to know what you really need and set the expectations right whether it is rankings, traffic or sales.
So what do you think..Should SEO be really held accountable for bottom line ?
Disclaimer : I am the author of this post on behalf of Growia which takes SEO training classes in Hyderabad and written the same post on LinkedIn also.