I wouldn’t assume that, or rather, I’d say it’s more complicated. My feeling is a multiplayer game with fewer active users, the trolls tend to stand out more than when a game is healthy and actively being developed.
A reason for this is the mechanisms in place that once would have alleviated these issues, such as matching players of a similar MMR, no longer function as intended.
For example, QM, has to use more MMR averaging to create matches, due to the low player base. This is why you will almost instantly see “expanding QM parameters” for example. In the past, if you had a high MMR, you wouldn’t encounter players who throw games often, as they would have a much lower MMR than you would, as MMR averaging was less likely.
The same goes for Ranked, when we had Hero League, you couldn’t group with friends that were a lower or higher rank. As there wasn’t the population to support both Team League and HL, compromises were made, so we ended up with the system we have now, that can be abused by smurfing, etc., and rainbow matches are more likely than in the past.
As my account is 2k, so it is rare for me to be matched with new accounts in QM, ARAM is a different matter. In ARAM, I’m often matched with players who are on “new” accounts, but more often than not, they are smurf accounts. In particular, many of these players a toxic smurfs, players who create an account for the sole purpose to troll on.
That isn’t all supposition on my part, I’ve witnessed many “new” players say in chat that they are a smurf, and they plan to AFK or other disruptive and toxic behavior. In my B-Tag thread, you can see many examples of this, with low level accounts with Tag’s like “Imgonafeed”, “banned4times”, you get the gist.
I’m not dismissing your concerns at all, I now avoid playing in ARAM, as it’s more common for me to encounter players like this in that mode as the MMR rules there are very loose. Many of the problems you point to, are just symptoms of Hots decline.
Even someone with a moderate IQ would not be citing their appearance on the MVP screen as having a strong (or any) correlation with their skill or even performance. Just jump on heroes such as Azmodan, Nazeebo, and you will land that MVP spot for the majority of your games, win or lose.
The MVP screen is mostly meaningless as a tool to judge performance and skill.