Ninja Gaiden (3d) has no lock on and works mostly fine (although it also has shitty camera).
And even a game like Bayonetta you usually don't lock on.
Many of these games have a soft lock-on the game does automatically, when you input the general direction of an enemy, which tbh is the sensible way to do it in games with big crowds circling you, with enemies that die in two hits.
Lock on is too slow of a mechanic when you need to redirect attacks to the enemy behind you, mid-combo.
One of the reasons Souls games (heavily reliant on lock on) are so shit at handling crowd combat.
Didn't play the game yet, only seen a bunch of gameplay and combat "deep dives", but from what i've seen of the game, the shit camera is more of a problem than the absent lock on, with no transparency for objects in the foreground, and in general a complete inability to follow the action, which is further exacerbated by the action happening on the face buttons (so you can't keep your thumb on the right stick).
Giving the camera a bit of an AI, following the action better, and perhaps not having off screen enemies initiate attacks without a very obvious (sound?) tell, would probably fix things better than a lock on would.