Maybe so, but at the same time, you are also not looking at the big picture.
If we make playing bad games to the end a thing, which a lot of games (especially in low elo) are, then Riot runs the risk of losing a substantial amount of players. There are a lot of games that are simply miserable for everyone on one team, and there are definitely enough trolls or inters to need a surrender vote. Not a lot of trolls announce themselves in pre-game.
If you really want this, I challenge you to never EVER accept a surrender vote. It kills the game to remove surrender. League is a big waste of time if you're behind by too much. I'm sure you'll enjoy your hellhole games.
As to 'enabling that behavior', that doesn't enable anything. Trolls already just afk. Do you really think they care about their games more than making other people miserable? If anything, removing surrender is going to INCREASE trolls. If they remover surrender, great, as well as subjecting average, innocent players to a terrible 30+ minutes, they also change NOTHING about the current troll climate. Trolls don't care about being reported, so why would they care about playing a game out? I've seen it more times than I want where they'll just afk anyways.