Now Google would have you believe just the opposite. I do not think they are disingenuous. In a large organization, it's all too easy for different groups to have different motivations. But ask yourself this, how much money does Google from Chrome? What does Google make money from? That's easy: advertising on search. And that is what is hold us all back.
If you have endured my purple prose to this point, I will finally cut to the chase. One of the most important aspects of any web page is how its PageRank. If your web page is all about deep sea diving, where does it surface when somebody searches Google for deep sea diving? The black art of making your page get a higher PageRank has given birth to an entire cottage industry known as Search Engine Optimization (SEO.)
As a developer I have never given much thought to SEO. I always thought that SEO was about the content of the page, and web developers are not responsible for the content. We are responsible for retrieving/generating that content from all kinds of sources, as well as creating applications that are easy and intuitive for the user to interact with a meaningful way. But, if we go back to the deep sea diving example, we're not responsible for providing information about deep sea diving. Heck you are lucky if most developers even known how to swim, but I digress.
But I was wrong. SEO is not just about content. It is about structure. If you want a good PageRank, then quality content about deep sea diving will lead to other people linking to your page and that will increase your PageRank. But there are much more instantly gratifying things you can do. For example, your page should a title and it better contain the term deep sea diving. No big deal, right? The title is really just part of the template outside of the main contents of the page. Its value has little effect on anything, besides PageRank that is. However, it gets worse.
Oh, maybe your organization hired an artist who created a killer deep sea diving logo and you load it on to the page as an image? Not good enough. If you put deep sea diving as the alt text, that will win you some bonus points from the Googlebot, but it is still dwarfed by the rewards you could receive by busting out the H1. Nothing compares to the mighty H1 tag. And don't just put that H1 tag anywhere on the page. Heck you might even get penalized for having more than one! Nope only one, and it better appear (in the HTML source code) as close to the body tag as possible.
Maybe you think that's going overboard, but it's not. Do you have a section on your deep sea diving page called "Gear" ? Then if you want to show up on a search for deep sea diving gear, you better have the term Gear wrapped in an H2 or an H3 tag.
There are tricks you can employ like progressive enhancement. There you do things the way that the Googlebot wants them, then dynamically obliterate that garbage and replace it with rich content that your users actually want. This can backfire. If the Googlebot figures out that you are tricking it, then it will banish you to purgatory.
What if you just make a great web application that users will love and don't bother to worry about the Googlebot? That's fine of course, it just means that people will not find your application by searching for it. Is your business model and marketing efforts robust enough to not need SEO? Yeah, I didn't think so.
So now do you understand? The Googlebot ties your hands, or at the very least makes you jump through all kinds of hoops. There are all these great technologies you could use to make your site as interactive as any desktop application, but The Googlebot does not like this. You've got to play his game whether you like it or not.