I dunno, my experience is I do it on a reasonably regular basis and it has worked up to low gold for me. In bronze an silver people let any lane they aren't grouped in build up during mid game. It doesn't necessarily mean the team is going to lose, it just means it's low elo.
Also like I said as long as one or two carries have gold, then if there's a third they don't need to have much for you to win in lower elo games. A five or six item top lane carry and ADC (or mid), with a 4 or 5 item jg tank and a 2 or 3 item mid (or adc) is probably more likely to end the game than the same primary carries w/ a 3 or 4 item 3rd carry and a 3 or 4 item jg tank. You only need so much damage to win the fight, but you need a tank to stay alive long enough to keep the carries up to do the damage.
Then again people in low elo complain if the support takes kills, and my experience if you can carry w/ annie support taking kills bot lane bc annie gets gold to initiate and burst down out of position carries, and the ADC gets ahead in levels and CS so they build a gold advantage anyway (unless the ADC is bad and getting out CS'd in a lane you're winning in kills, in which case I don't trust an ADC who can't CS to carry and I'd rather do burst damage from Annie support, and let mid and top clean up the kills for the team).
You're free to disagree, I'm just saying my experience, which may be different based on MMR. What I'm saying may not apply when you get past gold and go higher. Not sure bc I've only played bronze 3 to gold this season and haven't been higher.