Function creep. It doesn't have to be as bad as Duchene, but it's taken to the extreme. Unlikely to happen again, but, BUT, if it did, in OT, in Game 7, for the Cup, can you let the goal stand if it happened in that situation? Could say well hey, if the ref doesn't see it, too bad. That's legitimate, and everyone will move on with life eventually, but it would be, OMG, the NHL is bush league. The refs are awful! They have to replay the game! This is a corrective measure to that. Is it being abused? To the letter, no, to the spirit, probably yeah.
Why have linesmen? You can flip it, and ask, why have the technology to review plays if you're not going to use it to its fullest extent? If a play is technically offside, well, you know. Winning and losing can be the difference between a few million here and there. You can then ask, why not go back and review a bad tripping penalty? Then you can ask, why have human refs that make mistakes? Let's automate the refs, get more precise "eyes" everywhere, and decrease the amount of mistakes in real time.