There are more types of websites than just content based websites and sometimes websites who have to compete for the exact same content. The one who understands internet marketing the best will have better rankings than the ones that don't. A webshop selling airline tickets won't rank better if you add "interesting content", thats just not the way it works. Also the "interesting content" might distract people from what they have to do, order tickets. People have to realize that internet marketing is here to stay and it is something you have to think about.

Also your statement about spending time on interesting content gives your the highest ROI is not true. Hollywood and the game industry prove from time to time that they can create hypes and market B quality productions and still make tons of money. This also counts on the internet. Content is evaluated by machines (Google, Bing etc) who determine if it is interesting or not. Doing A/B testing to test which landing page works best is better time spent than spending your time hiring people to create interesting content. Just changing your button can increase sales by over 100%.

Ask the developers in the appstore whats more important, interesting content or a position in the top 5.

I'm not picking on you here: I think one of the reasons this issue gives us fits is that we think about it in terms of "gaining and sustaining traffic", which is somewhere in the general vicinity of an actual business goal, but not quite there. "Traffic" is not valuable per se and often people optimize for it in ways which are counterproductive for the business. For example, if you get featured on TechCrunch, you will certainly get a lot of "traffic", but what does that get you, really? A few dozen comments saying the design of your front page would look better in blue, your VPS chugs under load, and "didn't Taxi.derm.me already do this last year"? And then tomorrow they'll have forgotten about you.

But people spend insane amounts of time and effort trying to get on TechCrunch, when they could spend that time writing pitches to blogs whose owners will melt to know anyone who is reading them, or writing systems to make pillar content which will be attract qualified, interested prospects for the next decade.

And even for those few (arguably) lucky folks who make it onto Techcrunch, they might assume that if getting a big splash "gains" traffic then subsequent big splashes are needed to "sustain" it, throwing an increasing amount of resources to further pessimize their business to fit the preferences of a narrow, fickle audience who does not spend money on the stuff they have to sell.