There was an update that "ruined" pures/skillers when the combat level system went from the 200 max level to the 138 max level we have now. You could still be a level 4 (the minimum combat level) while having 99 hitpoints, 99 prayer, (and summoning?). However, when it was reverted to the 138 max level, those listed skills once again affected combat level. In reality though, it doesn't matter. Pures are disadvantaged in practically every single combat situation outside of combat against other pures.