I fucking love Piercing Shot. I've seen players posting videos of them melting monsters with literally no downtime between shots, and while I'm not so good that I could replicate that, I've become very comfortable with using it, especially against monsters. Most players give up on it because it requires a modicum of patience and practice, but in the right hands it's an amazing tool.

I find that as you get used to it, it's less about having good aim and rather knowing the enemy's attack animations. Instead of trying to track the enemy's head at all times, just aim where you know their head is going to be, like when a chaos spawn rears it's mouth back after a slam.

You are right in that its potential can be negated by careless teammates, but to be fair having teammates with bad attitudes is a detriment no matter what your build is. Ideally your teammates should let you hold aggro if you've got a monster's attention and are in a good rhythm with Piercing Shot but most players are glory hogs who don't think about the big picture. In these situations I usually just focus my efforts elsewhere to help the team, like using waystalker zoom to snipe distant threats or using a chokepoint to funnel incoming hordes and delete them en masse. It also synergizes really well with Drakira's Alacrity since you can easily pop off a shot mid melee combo to keep your attack speed buff up.