There isn't anything to say you can't but if you are using the points system to allocate ability scores then you would get a character who was strong but more or less average everywhere else.
Dreadfully expensive .. but worth it for some builds.
Rogue or Ranger (ranged weapons) use one stat for attack, damage, as well as reflex, AC, and initiative.
Other classes are somewhat less able to specialise (though builds with a 20 can still work well enough).