Advice Please - Invisible 'Barrier' during Boss Fights

[Rongway]

I don't think I can do that on controller. What's the benefit of it?

All that happens when I activate auto-attack or do an auto-attack-triggering skill is that it gets the auto-attack marker.

I think on controller it's neutral left stick click or something. Lock-on was originally primarily intended for physical jobs that needed to maintain target facing for auto attacks, parries, and blocks. While locked on you continually face the target and your left and right movements will sweep you around the target in an arc. However, since auto attacks, parries, and blocks no longer require target facing as long as you are not Bound, there is no real benefit to locking on anymore in most circumstances and it comes with the very large downside of being forced to backpedal while locked on.

It has some niche usefulness in aiming cone or line actions that do not auto facetarget. For example, to turn RPR's Egress action into a true backstep that teleports you away from your target, you might use the following macro:

/lockon on
/facetarget        //might not be necessary; I included it in my macro just to be extra sure
/ac "Hell's Egress"
/lockon off
/micon "Hell's Egress"

That way even when you are running left or right you can Egress away from the boss. The PLD wings can be auto-aimed at the party with a similar macro, assuming you are lined up between the boss and the party; this is slightly faster and more reliable than getting into position and manually adjusting your facing.