Why do people quit all the time?

In my case these are the main reasons...

I cant find a weapon, I die and my team mates arent even close.

Both of the team are downed, and the thirds one is still looking for a weapon or looting.

I get gang downed and finished and my team is almost next to me.

After a terrible drop from one of my mates and get killed immediately.

I get downed, my team wins, and they start looting instead of reviving.

I never leave a game while in the legend selection room no matter who I get to play with.

I never leave a game while in the jump.

I have been left several times by others, even parties mostly because I guess somebody picks their favorite legend.

I am level 77 right now.