Dynamic Queue and role selection aren't the same thing
Dynamic Queue is "less toxic" than old SoloQ because you're allowed to pick your role. If you play exclusively solo ranked, you've had plenty of games already where your team was full of solo players who chose their role before the game started and everything was fine. The "toxicity" in solo queue was because of the combination of "pick order vs call order" and then not being able to do anything about it after someone locked in anyway.
If they were to bring SoloQ back, there's no reason why they shouldn't still include role selection. You can want a dynamic system that only lets you queue up as an individual. The only thing "dynamic" about it is the match making.