I see this Post as more or less a rant because it sounds like you’re not doing so hot.
I was playing earlier today as my Scout (as opposed to my regular Berserker) and noticed that if I engaged too hard my Lifebar melted away. I had to stalk from a distance and engage from a distance with my Bow instead of going all aggro. The Match lasted longer as well. But holy crap can the Scout move. Their speed is their best asset.
The AI is only a problem when they gang up on you. And if they set the Alarm off, you’re being too sloppy. I had one Match in particular where I saw the last Fireteam Member get downed inside the 2 Story Building at the Dishes in Backwater. I ran in without paying attention and immediately Long Claimed. I was then melted by about 9 AI Grunts, Firing Squad style.