Just because something is good for my business, doesn't mean it's good for society. SEO (beyond actually making your site more valuable) is a classic prisoner's dilemma.
I think this is where my views differ from many on HN. As a business owner, I will do whatever is best for my business, without regards to what is best for society. My job is not to worry about what is best for society -- that job belongs to the government. The government sets the rules and we play the game. As long as I am not breaking any laws, I will do whatever it takes to bring my business to the top. I have to do this because if I don't, somebody else will. Riding a moral high horse will only lead to my business being stampeded by others who are willing to engage in tactics I am not.
This is not to say that I actively work against what's best for society. My point is that I will do what's best for my business, with regard to nothing else. I think that is what makes a good business owner. Another trait of a good business owner is the belief that his business provides the best value in its market. If you truly believe that, then by engaging in SEO to rank your business at the top of its market, you ARE doing what's best for society. If you suggest that engaging in SEO tactics to rank your business at the top is BAD for society, then you are inherently suggesting that your business does not provide the best value to its market.
I sympathize, but take notice that this is part of the classic one-two strategy that capitalists, as a class, have historically used to gain a disproportionate amount of power in certain historical periods. Say, the 19th century, or the 80s/90s. Not with malice, or even consciously, of course, but it's worth to watch for it, lest we fall again, and again...
First, claim the reasonable principle that law should guard morality, and business should attend only to business. It's in principle correct, so it gets accepted by everyone. So, if child labor were allowed, business owners would be in no moral fault for hiring kids to mine ore -- to pick a extreme example.
Second, claim that economic progress is good for everyone. Again, very reasonable. Then, organize as a political class (say, in nowadays Republican party) to get some legal concessions that were morally abhorrent in the past legal framework, in more or less degree, but would bring economic progress (for some definition of it). Say, legalize child labor. Voilá.
Now, it's obvious that capitalists should be, of course, allowed to organize politically. But, I argue that we live in a world disproportionately controlled by capital (specially the US), for various reasons. It's disingenuous, thus, to be a capitalist and have your mindset. You, as member of a class, have certain privileges that other classes in our society would consider unfair. Our current legal framework is loaded in your favor, after all.
The "if you don't, then somebody else will" argument only applies if you're in a commodity market: A market with a lot of players selling the same product, or a market where there are few barriers to entry keeping out people who sell an interchangeable product.
Much of the world inhabited by HN'ers is not like this. If you have a typical software or web product, then a competitor would have to spend substantial resources developing code that duplicates your functionality, and then they have to worry about the head-start the first mover has in branding and network effects.