Whenever I, as a reader, do a search on a particular subject, I generally click on the top several results.
However, should the top result/s be a badly-written article chock-full of totally unnecessary key words jammed into the copy in a really ugly way, then my reaction is to curse, hit the back button and look for another site.
Recently I searched for a hotel in a particular city and the first result looked like it should have been ideal, but when I was faced with nonsense phrases that ruined the flow of the article (complete with the all-important SEO hyperlinks!) like: "Hotels,London,England" I immediately used the back button on my browser and found the information I required on a different site.
What did this mean? From the Idiot SEO point of view it was a success (the website had gamed the search engine, after all) but from the marketing department point of view? It had been a total and unmitigated disaster!
It had alienated me, the visitor and sent me off to the arms of another site which will get my business.
And I will almost uncertainly not bother to visit their website, again.
So, should you use SEO? Yes. Certainly. But you would be advised to avoid using Idiot SEO. Unless you want to send business to your rivals.