Color of Choice in the Most successful Web-based Startups is a Reflection of Something?

Looking at the first page of the most successful Web-based startups of the last 10 years (e.g., Facebook, Instagram, Twitter), we see the extensive usage of the color blue. In terms of the graphic design, is there any technical meaning behind the color blue (e.g., social interaction, trust, 'coolness')?; or is it just a coincidence?