"dynamic queue is better for high elo players"
-->can't have role selection -->can't play as a team of 5 for better quality of games -->possibly playing with boosted people -->possibly having a higher queue time.
"better for high elo"
https://66.media.tumblr.com/8cf76771d8b22b7bed46206bd2a765fa/tumblr_mmvj9mJl7q1souohbo2_500.gif
top (my old main) your adc is 0/5, their ADC is 5/0 protected by 2 of his premade who picked hard cc tanks? your adc can't do damage and you can't kill their ADC.