It's no more silly as every Starfleet officer being a graduate of Starfleet Academy. It's just one of those things, is all. In order to get the attention of the common viewer, recognizable names have to be used. Therefore Earth Vulcan, Qo'nos are used since they have more recognition factor among the audience than Alpha Centauri, P'Jem, or Mempa VI. The closest you get is a compromise like with Tuvok, born on the Vulcanis Lunar colony but raised on Vulcan.
C.E. Evans wrote:
Worf was born on Qo'noS, but he and his family eventually relocated to Khitomer and made that Klingon colony their home.
Actually, Worf and his parents were visiting Khitomer at the time of the massacre and had left Kurn behind on Qo'nos. However, the Rozhenkos were living on the colony world Gault when the adopted Worf, though they eventually moved to Earth.