well, maybe having an endorsement or two (or three...) says something (although very little, in my opinion) about your capabilities as a musician, but it doesn't follow that those who have more endorsements are better musicians/artists. some people simply don't want to be tied up to a particular brand. they'd rather enjoy the freedom of being able to use any brand they wish. some people don't need an endorsement deal to stay loyal to a particular brand. some people who don't carry endorsements can actually kick the ass of one who carries several.
as a general rule, the amount of endorsements is not an accurate measure of an artist's capabilities. it is just a measure of how infuential he is, at least according to the companies/brands he endorses.