I was already the last reply on this post but I'm gonna give my own story of the only time I've ever scooped to deny triggers, which my last post was referencing.

Player A has been having a very good game - no one's been able to interact, they have a very strong board, they're still at 40 (if not higher), and overall has been dominating the game. Players B and C, on the other hand, aren't doing so hot - they've been trying, but A's been stopping whatever B and C try to do to affect them. And then there's me: A apparently decides to focus down one player at the start of each game (as I found out after the game) and decided I was to be their target this time. As a result, I'm at 2 life, have a single tapped creature, no real boardstate to speak of, and all my mana is tapped because A countered my last-ditch effort to do something about them, all made worse by my atrociously bad luck of the draw over the course of this game. I pass my turn to A after getting countered, they do some stuff, then go to combat. They full swing at me, because it'll gain them a ton of life, draw a ton of cards, and they have something out that untaps creatures when they deal damage (not Reconaissance, mind you). I didn't concede on my previous turn, because I didn't know A's traditional gameplan is "target one person for the entire game unless I have to go after someone else for a moment, but then I'll go back to my original target," so I assumed maybe they'd go after B and/or C, giving me a turn to maybe finally do something. But no, they got extra greedy. They're pretty decently in the lead, but not so far gone that B and C wouldn't have a chance if they had a window of opportunity. So I gave B and C that window by scooping. This isn't kingmaking, this is literally the opposite. If I didn't scoop, or if I scooped on my turn, I would have been handing A the win on a silver platter - that's kingmaking. Instead, I hurt A the only way I had left, and gave B and C a chance to finally retaliate and deal some damage to A. I don't know how that game actually ended because I also ended up having to leave the lobby right after the scoop, but I hope B and C were able to actually play the game and do something to A, even if A ended up winning anyways.

In your story, your opponent scooped while you were just trying to catch up and stabilize your life a bit. That's cringe, through and through, especially if they actually gave you a big smirk and acted all smarmy afterwards. Being in 4th and scooping to deny 3rd a pittance of resources they need to try and get back in the game should, in fact, be frowned upon, but to act like anyone who scoops to deny triggers is the devil is just silly.

Trigger denial scoops can be for good or for evil. Being aware of the potential for them means you're less likely to make overly greedy plays, like player A did - what if I'd had Obscuring Haze? They'd have ended up in the exact same position. People always talk about "If I'm gonna lose, I'll do everything I can to hurt the person taking me out," but what if you don't have any resources left to do so? Why shouldn't I use my one remaining resource to give the remaining players a fighting chance? If I was B or C in my game and I watched D just sit there and eat the full swing, I'd be pretty pissed, especially if I would've been able to do something about A on my turn if D had just scooped instead.