The answer is because the Google algorithm is very sophisticated in terms of what content is deemed to be of high quality.
This is described in great detail in a document Google titles the Search Quality Rating Guide.
Allow me to summarize (and this is the ultimate in being a condensed version).
Search Query and User Intent
For every search query, the user has one of several intentions (per Google). They are trying to do something, learn something, or find something.
Webpage Usefulness to Search Query and User Intent
Relative to the search query and the user intent, the various pages on the Internet provide varying levels of usefulness.
Google uses a four-point scale. The ratings are:
- Slightly relevant
A very small site with very few pages CAN be the most useful page on the entire Internet relative to one or more specific search queries which imply a certain user intent.
A small site outranking a larger site is the exception, not the rule.
In general, for most search queries, sites like Wikipedia and news sites (industry news sites are still news sites) tend to outrank business blogs.
Because Wikipedia and journalistic (is that a real word?) sites tend to be what the search engines find desirable.
They are very large repositories of quality (as in useful) content that is updated very frequently.
When you’re not lucky enough for your business niche to contain very little competition, your best strategy is to turn your business blog into an online magazine catering to your desired audience and publish good stuff frequently.SEO Needs Link Building