Why is it so much harder to climb out of bronze than it is to climb to crystal?

[Multisensory]

Primarily because the higher in rank you go the more basic competency and general knowledge of the game mode your teammates will have. Anything from basic stuff like understanding how Overtime works to more nuanced stuff like knowing not to shoot at an enemy at full health when your teammate(s) are low and pursuing one of the health potions on the ground. As people start to understand these things, they are more likely to win, and thereby get to higher ranks making for a much more coordinated/less chaotic fight.

Silver was a nightmare for me. But once I got out of it and into Gold/Platinum, team play became much more consistent. At least until I hit Diamond where the inverse seemed to occur and now I'm playing with people who seem to forget that Ninja/Dragoon should be primary xD

That's funny. In gold, I find people to be even more brain dead. I literally have been stuck at Gold 4 for two days now. Whoever designed this system is so incompetent