Sounds good in theory, but probably not going to work in practice.
If every game people follow the same team composition, then the items build for each game for each role would be very similar. And that take away the fun from the game. For example, if I pick Irelia solo top in a game which the enemy team have the standard team composition, I would almost always get Mercury's Treads. However, let's say if the enemy team have 5 ads (i have seen this alot, since everybody wants to "carry"), then i would be stupid if i buy Mercury's Treads. Therefore, i always counter-build my champion in a game.
On the other hand, if there's only one troll in your game, you're not likely to lose. The reason is since they fed the enemy so much, killing in again will not give them that much gold anymore. What you have to do, though, is communicating with the rest of your 3 teammates, have a 4 on 5 fight. It is definitely hard, but if you know who to focus first, then it is do-able.
So my point is, having a troll on your team is a bad thing, but it would definitely make you a better player, since you're more likely to do stuff such as buying wards, communicating with your teammates, gank more often, push together,and last but not least, counter-build, to try to get back to the game.
And another thing is, what if your team have the proper team composition, one jungler, and one solo top, but the enemy team have 2 ranged at top? your solo top can't farm, and you can't gank, since they can kite you. you lose the game by following the proper team composition.