Well various strategies actually work and also kinda depends on the enemies if you are facing, being at the choke point when facing the demon champion can be a bit of a death sentence if you got a lot of melee characters in your team... That demon champion is way too OP, AOE stun/fear and then literally either kills your team or weakens them to the point they can't survive... The other two champions are no where as bad. Half the time I don't blame people for bailing out at the begining of the match when they hear they have to fight demons.
The main thing is not to get overwhelmed in the fifth stage, sounds easy enough, but not when oyu have a pug and/or very undergeared players...
At the moment everyone is still very lowly geared so things will remain quite tough for a while til everyone starts unlocking/obtaining those more powerful weapons..... The same thing happened with Mass effect 3... Early days everyone was using rnk 1 commmon weapons that hindered people a lot more many of the vets take for granted these days. Heck even using an ultra rare weapon at rnk one surpassed many of the uncommon weapons at rnk 10 (generally) for mass effect. It will take a few months before things even out
I know when I picked up my unique lvl 16 double handed weapon, my reaver suddenly turned from a puny mouse to a bloody monster! So just give it a bit more time till people get better items and start understanding their classes and gear more. A lot of teams still don't use combos or synergised attacks