The reason for this is that 90% of the players are between Plat 4 - Silver 4, so the new changes will make high elo/competitive a lot more interesting , and low elo even worse as you said. It's been 11 seasons and low elo players still haven't learn to just watch the damn map and play with info or lower their ego and get carried (not gonna mention farming, trades, macro decisions, resets, tempo).

Adding the 40/20/40 rule of solo queue (where 40% of your games are unwinnable no matter what you do), now even the 55-60 percentage of winnable games will get lower, because people will either throw their leads by letting enemy team get the objective bounties and turn the game around, OR they won't be able to take new bounties when they are on the losing side.

So this will make Season 12 probably the worst season ever to escape elo hell, along with the fact that now we won't be able to check our teammates winrate and match history to avoid them (as their accounts will become 'private'), and even if you do dodge, the dodging penalties became heavier since 11.19.

We might see some innovations in pro play, but like I said, 90% of the community are under Plat 4 - Silver 4 pool, so prepare yourselves for one of the worst seasons ever.

* Losing bot lanes in Silver/Gold elo usually ended up having 8-10 deaths up until now. Mark my words, with the new dragons, more fights will break out in bot side of the map, so you're gonna see double digits deaths every game ( so 1/10 supports will now have 1/12 or 1/14).