How can someone soft int? It's either intentional or unintentional.
I think people view "soft int" = "died a few times, got discouraged and isn't trying to win." However, "giving up" is its own category, and is different than inting.
Sometimes there are games where your lane opponent has such a big advantage, they can tower dive you and keep killing you. It's frustrating for the person you're clamoring to report, too. I had a game a month or so ago as Kayle vs. Garen, and Garen was just dominating me. He got two early kills and at level 6, he could just walk under tower, kill me from 100% hp, and walk away, all with half of an item. Seems crazy that Riot makes champions that can do that, but they do, and because no one on my team wanted to help me, he took all 5 plates, had a 15 minute triforce, was pressuring Tier 2 tower, and I was 3 levels behind him. So if I can't even sit under my own tower, what is my alternative if my teammates won't help me? If you abandon your teammates to their fate like this, that's as reportable as the person who is dying (spoiler: I don't think either are reportable). Bad games happen.