Healers who rescue pull tanks into mobs.

[Packetdancer]

Rescue literally stops everything you're doing, takes control of your character and displaces you. In a game that's all about strict rotations and positioning that's probably the most annoying, intrusive thing one player can do to another.

I personally have seen jerk tanks troll with Shirk in Light Party content more than I've seen Rescue misused. It still hasn't been often—I'm fairly sure it's less than ten times total since I came back to the game last August—but I've almost never seen Rescue even used in Light Party content at all. (I grant that like... 64.7% of the time the healer in a Light Party I'm in is me, so this does potentially skew my personally-observed data set.)

Rescue may be intrusive, but it does have an intended use even outside of raiding (and a use which sometimes is the difference between "welp, they died" and "whew, that was close"). It's clear that people don't like that use—and I'm going to try to take that to heart and just let folks stay in the bad/run off with the stack marker/etc. in the future rather than disorient them by pulling them to safety in the last couple of instants, because it's not the end of the world if we die or the party wipes—but there is an intended use which falls within what a healer is supposed to be doing in a party (i.e., keeping people alive).

In contrast, Shirk is potentially a 'vaporize' button for killing people in your own party; that's also pretty annoying and intrusive on your gameplay, and there's far less justification for the skill to even exist outside of endgame raiding.

tl;dr: Rescue has a potentially useful intended purpose which some people vehemently dislike, but you can see a place for it in what the devs wanted in game design/balance. In easily 95% of content, Shirk can literally only be used to troll other players, so there's absolutely no rational reason it should be even possible to use it outside of endgame raiding where you need to tank swap.

Edit: I would honestly prefer just removing Rescue to a toggle, personally. If it's a toggle, then I always have the possibility that if I select someone and use Rescue it just won't do anything if they have the toggle on. In which case, I've just wasted time I could've spent on something else. If Rescue's gone, I know that I have no options for saving someone there, so I don't even need to try it; if they die, they die, and I'll rez them when I can.

(And moreover, if Rescue's gone and I have no options to save someone in those situations, it saves on party chat blaming a healer for not pulling someone to safety. Which actually happened in Grand Cosmos the other week, when I didn't pull a SAM over to furniture to get rid of Mortal Flame and got yelled at in party chat by the SAM because "a good healer would see I wanted maximum DPS uptime and save me having to sprint across the room". I mean, the issue here was not Rescue but that the SAM in question was kind of a jerk—if he wanted that DPS uptime strategy he could've just told me ahead of time—but if Rescue's gone, it'd have been his problem and not mine.)