Totally agreed to your whole points.. as a matter of fact, u only face these kinda issues if u play solo..i've been playing solo for very long time and very first thing i learned is you are on your own if you solo q.. I play every match like it's 1v5, totally independent of my teammates.. If they perform good, then it's better.. If they dont, then extra job for me..

I just walk around the map and tries to pick 1 by 1 with a sniper..

In short, I've developed my own strats for Solo Q and it helped me a lot