Why Class A means the transistor conducts for the entire 360 degrees of the input cycle, so the quiescent (no-signal) collector current must sit far enough from both extremes that neither peak of the signal clips. On the DC load line, saturation is one end (maximum current, minimum collector voltage) and cutoff is the other (no current, full supply voltage); biasing at roughly the midpoint gives the largest symmetrical output swing and the lowest distortion, at the cost of steady power dissipation and efficiency under about 25-30 percent.
Watch out The idea of sitting halfway between emitter and base voltage confuses the base-emitter junction drop (about 0.7 V in silicon) with the Q-point, which is defined by collector current and collector-emitter voltage on the load line, not by that junction.
Class A = always on: park the Q-point mid-load-line, halfway between saturation and cutoff.