A multitude of problems contribute to the situation, including: class imbalances (DRK, in particular), premade parties (coordinating attacks to maximize damage whilst hindering any attempts to stop/prevent it), player attitude (defeatism upon realising they're against a premade).
I enjoy playing with friends and would rather a different solution than just to ban all parties and make it a solo queue, but if that's what's needed to prevent premade teams (as they will no longer be able to queue together and guarantee being in the same team consistently), then I will go with it. Premades have become far too much of an issue to ignore any longer and to let them continue will only push casual / solo players further away from FLs.
Some random teams are excellent at coordinating their attacks but, regardless of how good they are, they still do not come remotely close to the coordination and advantage that is obtained by premades. I totally disagree with your suggestion that a random team can achieve the same or better results than a good premade. A bad one, perhaps. But not a good one.Being able to coordinate with people is obviously an advantage, and being able to do so with people in a pre-made is also much easier. It still doesn't change the fact that you are still able to do so with or without a pre-made. I'd argue that being able to coordinate with the other 20-23 randoms in your alliance is much better than an individual pre-made. If you have a game where you just have some guy who can easily just do callouts to tell the entire alliance where to go, that is far more effective than a 4 man pre-made coordinating an LB push to win one fight every 90s at most.
Because even with how annoying it is to go up against those people, those 4 players can't possibly carry an entire team to victory if no one is actually playing objectives and farming BH off of the leading team.
I've covered the names of all for anonymity, but I don't need to point out which are the premade.
(I would add - this in an Onsal Hakair match which didn't have too much time spent in the centre platform, so most of this was obtained on quite open areas of the map.
Now imagine what the scores would be in somewhere like Fields of Glory or in a Onsal Hakair match which did have lots of time on the centre platform.)