I have come to the conclusion that Search Engine Optimization (SEO) does not matter anymore, at least not the basic stuff such as optimizing your site tags, content, performance, and navigation. The reason I believe this is because everyone else is doing this, including your rivals, so you are not going to stand out from the crowd. That playing pitch has leveled out years ago.
Google make their money from advertising your site, not from sending you free traffic via SEO. So you need to take out your credit card and buy some Adwords in key search terms for your business, as that is what Google wants from you. There is no more free lunch. I believe we are already in the post-SEO age of the Internet, maybe we have been for a few years now.
SEO was supposed to give you a competitive advantage, with your highly-optimized site appearing ahead of your (supposedly) less-optimized rivals in the search rankings. With the majoring of above-the-fold space on Google being taken up by ads for popular search queries, those looking for free traffic via organic SEO are really just fighting for scraps. The only exception to this might be large, established brands that already have a high page rank, but for newcomers it is bordering on impossible to get meaningful free traffic from Google.
For the past few years, the companies I have been working with have been competing for rankings on relevant search key terms on Adwords with their rivals, meaning the guy with the biggest advertising budgets wins (and Google wins either way). Organic SEO does not suit Google, in terms of their business model. They want you to pay for placement.
Most people will just click on the first few "results", even if they are in fact ads. They can hardly tell the difference. That's why businesses are paying so much to be on top of certain lucrative search key terms: if they we not getting a return on their advertising spend, then they would not be spending it.
My main point is, even if your website is horribly un-optimized in terms of SEO, if you have a bucket of cash to spend on Adwords, you will still get a tonne of traffic. SEO in this instance is almost irrelevant.
I consider SEO at this point to be about breaking even with the search engine bots: if you don't do it then they might actually penalize you (e.g. your site is slow, you have broken links, broken redirects etc.), but if you do optimize then they will at best take benign view of you, but not necessarily a favorable one.