It can be used that way, sure, and the Very Civilized Starfleet uses them conservatively. But a beam weapon that is capable of disintegrating anything (unshielded) that it touches is crazy powerful. And those are only the hand phasers; we don’t often see the phaser rifles, but holy heck. If phasers scale like projectile weapons do, a single phaser rifle would be capable of vaporizing entire buildings, tanks, aircraft.