You say this like you've never played against a team of 20 people that maybe had half a brain between all of them. More often than not if a team notices they have a strong ranged advantage they are (perhaps just barely) bright enough to realize that ranged players are stronger at a distance, and will therefore hold back and play more defensively. Then your team's 2:1 melee advantage will dwindle down to maybe a 1.5:1 advantage after 5 guys get picked off on while closing the gap. Assuming that the fight is perfectly even, and 10 melee players die on each side, then it's 5 battered and bruised melee players vs. 10 ranged players with full health. Those aren't very good odds even if all the ranged decide to engage in melee combat, which they won't.
I was going to write something sarcastic but i couldnt pull it off sorry, anyways:
Youre writing this assuming the melee based team would be charging, why should they be charging the ranged teams melee in this scenario? While many people do love to charge mindlessly, in theory if people hold, wait for flags, then the melee based team will simply win because ranged just doesnt do much damage, atleast not fast enough to be of help trying to get flags.
Otherwise both teams generally have some people charging, who get continuously backed up by more teammates, untill one team is runs out of melee, and then its either a patience game or mow down ranged, depending on team builds and how big the clash was won. At this stage it usually looks like its the ranged doing all the work on the winning team, because a lot of them will still be alive since their melee won they wont really be put in too much risk. But in reality, the infantry did the majority even though many of them are dead. Ranged does help, mainly with taking down cav, but against infantry it seems like a good stagger is the most they'll do.
Also i have quite a lot of hours put into this game, please dont assume that i lack experience in this game. Pretty much never have i lost a battle in the recent years and thought it was lost due to ranged being overpowered, or even strong for that matter.