e.g. you have the keyword digitalpoint and search on google for it, why digitalpoint maybe appear on the 4. position and not on the first, i think when a domain includes an keyword, it is more important for google, or?
nope, the highest ranking web page for any search will be determined by googles algo based on a large number of criteria For keyword domains, the name of the domain probably matters even less if many other sites are targeting that keyword
Having you main targetd keyword(s) in your URL helps, but as centime said, it's just one of the many factors Google looks out.
I think a domain containing keywords helps a lot. My 3 weeks old site is the 65th in G for the keyphrase "seo links" (among 48 000 000 competitors). I think it is dued to the nice domain.