i think that it has to do with the meta, go watch seasons 2-4 and how long it takes to kill people. It took multiple people focusing 1 person or more than 1 rotation of spells. Now you are able to blow people up so fast even when behind. tanks do not really exist while bruisers can do their job of being tanky and a ton more damage. ADC die to a stiff breeze and deal so much damage I wonder how half the time of how did they die so fast(enemy). I've been blow up in .1 seconds from a brush with 100% hp by 1 person, it really isn't fun to not be able to react. It makes sense to smurf since its like entering a team death match while you have an AK and everyone else is using knives.
Personal things I would change
CDR is too much
Damage is too much
Defense is basically useless
Towers are made of paper after plates drop
Baron buff is too game changing for how early it spawns
Elder Dragon is too weak for how late it spawns (if you even see it in game)
Snowball is so high because of lack of defensive options (get 4 kills in 20 min and you can pretty much 1 shot anyone)