I'm not sure I would even say this is just a matter of following the meta or not, but more of a case of putting your team that wants to follow the meta at a disadvantage, and trying to force them into a situation they didn't go into when they picked (in your scenario as the 5th pick refusing to conform to the other 4 people).
If you want to try something new, let your team know, and to a degree that can be hard given the minimal amount of time in champ select, but there is no positive result ever, when you, as in your example, are last pick and just pick what you want (as far as double jungle for example) when you made no mention of it to your team, or they disagreed to trying it.
You are annoying your teammates, they won't want to help you, likely going to start arguments, and you have a much worse chance of winning even if logically it could work, because they might not want to even try, and just call you a troll.
What's the point of trying to force 4 people to conform to your play style (especially in ranked, because yes ranked and normals are two very different animals), especially when they likely wouldn't want to do that? It is not only selfish, but is just creating a negative atmosphere for the entire game.
An unconventional champ is one thing, but trying to force a team into double jungling, double mid with no jungle, two adcs with no support, etc, will likely never end well.
Also for the most part, all of this can be fixed to an extent with team builder (or it should to an extent). The problem is the fact that someone always has to be last pick, and that person could be say, a Doublelift alt (just throwing out a random name). No one else is going to care who he is if they don't know him by name, he could be the best ADC in that division, but some Bronze 3 player wants to adc, so...Doublelift is last pick and gets stuck jungling. Guess that could start an entirely different discussion.