I think the main issue your driving at is what is called "barriers to entry".
Every business has barriers to entry and some more than others. For example, if you wanted to start an oil company, the barriers to entry are quite high, because you would have to invest in huge start up costs such as billions of dollars worth of property, plant and equipment (i.e. Oil refineries, drilling equipment, technology for finding oil, Tankers, etc...) So the barrier to entry for an oil company is quite high.
Now look at the internet. There are very very few barriers to entry, which is what makes it such an attractive marketing medium for people on low to no budgets. And since the web is a global digital network, it creates a truely even playing field. Mom's website blog can be listed right along side CocaCola's official website in search engines and directories.
Barriers to entry for a web business are:
1) Technology: (most of which today is readily available such as database drivin content management systems, free blogging platforms, open source operating systems such as Linux, and Open Source web servers such as Apache etc..) There are a few examples of companies that have unique or original technology that gives them a competitive edge (google in search algorythems, Amazon for 1 click buying etc...) However most of these technologies can and are easily replicated once someone does it first (take Digg for example).
2) Content: the second element of a web business is your content, which could be in the form of text, video, audio, database, and or products/services offered. How a web company presents their content and the perceived quality of the content is what gives them a competitive advantage and create a small barrier to entry.
3) Brand and Brand Awareness: A stong brand can be a huge barrier to entry. For example, now that the word "Google" has become a verb in the english language meaning to search online for something, how difficult do you think it will be for a competing search engine to draw traffic away from that brand?
4) People and social networking: A company can have people assets that give it a compeitive advantage in the form of being able to easily raise venture capital (or not), being able to create strategic partnerships (or not), and being able to evangelize the site.
There are others, but you get the idea.
Basically the web is a level playing field that breaks down the traditional barriers to entry that one would encounter in trying to start a "brick and mortar" business. So that makes Google's job a lot harder in trying to sort through good from bad, or relavant from not relevant.











