The reason the statistics say there is less toxicity and fighting in ranked now isn't because of DQ

it's because of new champion select. One of the reasons why people raged so much before was because they were forced to go support, top, adc, etc. even though that wasn't their main role. This led to a lot of people feeding, trolling, and so on and so forth because they didn't want to play in a game where they weren't having fun in their preferred role.

Just look at what happened the moment Riot enabled the auto fill option for high elo games. People started trolling and raging immediately because they didn't want to support or top and just went their preferred role even though they got a different role than what they asked for.

The reason there is much less raging now is because that problem was solved with being able to pick your preferred role without having to worry about being stuck as support or adc or whichever role you are bad at. Dynamic Que has nothing to do with these statistics and is probably one of the factors that is leading to more raging and frustration.

No matter how you balance it out, playing as solo against a 3 or 4 man premade will never be fun. The only thing that needs to be done is to bring back solo/duo que and add the new champ select to that and replace Dynamic Que with 5 man ranked teams again. Riot's only real argument as to why Dynamic Que is better than Solo Que is because "muh statistics" and are really just making a claim with no proof to back it up.

Adding new champ select to solo que wouldn't help address the high que times for high elo players but neither does dynamic que.